* [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
@ 2006-09-30 20:35 Lionel Bouton
2006-09-30 20:58 ` Dominique Michel
` (3 more replies)
0 siblings, 4 replies; 32+ messages in thread
From: Lionel Bouton @ 2006-09-30 20:35 UTC (permalink / raw
To: gentoo-dev
Hi, I just had an unpleasant experience with -ffast-math and GCC 4.1.1
(it borked my LDAP authentication on several systems which worked with
the same CFLAGS as long as GCC 3.4.6 was used).
There is a lot of material out there about CFLAGS and Gentoo (google
returns 387000 pages) but what's working for someone might not for
another. There are flags that work for a GCC version and most ebuilds
and don't work with another GCC version (my unfortunate experience) or
some ebuilds. Flag combination/architecture/LDFLAGS might be an issue too.
There are already good resources (http://gentoo-wiki.com/CFLAGS_matrix
was mentioned to me by robbat2) but they may not be advertised enough.
I'd like to propose a paragraph to the GWN editor which presents some
gotchas and good references on the subject.
Here's a draft for review. You're welcomed to expand on the subject.
--- Draft BEGIN ---
<section>
<title>CFLAGS</title>
<body>
<p>
Being able to tune the CFLAGS is part of one of the core principles of
Gentoo: let the user be in control. Being in control brings both
benefits and problems and CFLAGS tuning is not an exception.
</p>
<p>
The recent upgrade to gcc-4.1.1 for x86 and amd64 users changed the
landscape. Users that spent some time tuning their CFLAGS with gcc-3.4.6
might find out that an upgrade to gcc-4.1.1 leaves them with an unstable
system. Example of this are :
<ul>
<li>nss_ldap stopped working with -ffast-math</li>
<li>...</li>
</ul>
</p>
<p>
Users with unsupported CFLAGS (see the <uri
link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
example) might want to return to safe CFLAGS (see <uri
link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
updates caused them stability problems. On the other hand, more
adventurous users might want to experiment with CFLAGS that didn't work
properly with gcc-3.4.6... As always, the user is in control.
</p>
</body>
</section>
--- Draft END ---
If possible, I'd like to expand the list of 3.4.6 -> 4.1.1 upgrade
problems which are linked to experimental CFLAGS. If you want to expand
the subject to cover other tuning/stability gotchas that recent updates
might have brought into the light, please feel free to do so. As English
is not my native tongue, feel free to spell check too.
Cheers,
Lionel.
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-09-30 20:35 [gentoo-dev] [RFC] CFLAGS paragraph for the GWN Lionel Bouton
@ 2006-09-30 20:58 ` Dominique Michel
2006-09-30 21:48 ` Mike Frysinger
` (2 subsequent siblings)
3 siblings, 0 replies; 32+ messages in thread
From: Dominique Michel @ 2006-09-30 20:58 UTC (permalink / raw
To: gentoo-dev
Le Sat, 30 Sep 2006 22:35:58 +0200,
Lionel Bouton <lionel-dev@bouton.name> a écrit :
> Hi, I just had an unpleasant experience with -ffast-math and GCC 4.1.1
> (it borked my LDAP authentication on several systems which worked with
> the same CFLAGS as long as GCC 3.4.6 was used).
>
> There is a lot of material out there about CFLAGS and Gentoo (google
> returns 387000 pages) but what's working for someone might not for
> another. There are flags that work for a GCC version and most ebuilds
> and don't work with another GCC version (my unfortunate experience) or
> some ebuilds. Flag combination/architecture/LDFLAGS might be an issue too.
>
> There are already good resources (http://gentoo-wiki.com/CFLAGS_matrix
> was mentioned to me by robbat2) but they may not be advertised enough.
> I'd like to propose a paragraph to the GWN editor which presents some
> gotchas and good references on the subject.
>
> Here's a draft for review. You're welcomed to expand on the subject.
>
> --- Draft BEGIN ---
> <section>
> <title>CFLAGS</title>
> <body>
>
> <p>
> Being able to tune the CFLAGS is part of one of the core principles of
> Gentoo: let the user be in control. Being in control brings both
> benefits and problems and CFLAGS tuning is not an exception.
> </p>
> <p>
> The recent upgrade to gcc-4.1.1 for x86 and amd64 users changed the
> landscape. Users that spent some time tuning their CFLAGS with gcc-3.4.6
> might find out that an upgrade to gcc-4.1.1 leaves them with an unstable
> system. Example of this are :
> <ul>
> <li>nss_ldap stopped working with -ffast-math</li>
> <li>...</li>
> </ul>
> </p>
> <p>
> Users with unsupported CFLAGS (see the <uri
> link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
> example) might want to return to safe CFLAGS (see <uri
> link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
> updates caused them stability problems. On the other hand, more
> adventurous users might want to experiment with CFLAGS that didn't work
> properly with gcc-3.4.6... As always, the user is in control.
> </p>
> </body>
> </section>
> --- Draft END ---
>
> If possible, I'd like to expand the list of 3.4.6 -> 4.1.1 upgrade
> problems which are linked to experimental CFLAGS. If you want to expand
> the subject to cover other tuning/stability gotchas that recent updates
> might have brought into the light, please feel free to do so. As English
> is not my native tongue, feel free to spell check too.
>
> Cheers,
>
> Lionel.
My personal experience with other CFLAGS as the ones in the handbook is at
gcc-4.1.1 have a better optimisation with the default gentoo CFLAGS. Even
with -O2, the result is a faster system, and -O3 seam to be safer with math
related applications as with gcc-3.4.*.
But in the other hand, other flags seam to be more problematic as with
gcc-3.4.*. And the new optimisations flags as the vectorisation flags are not
easy to use, because the result depend on the code of the program. They can or
not brake the code, and when the program run well, they can make it faster
or slower. All depend of the size and complexity of the loops. And I think also
of the arch.
So my conclusion is:
For system flags, just keep the default, and if you want to experiment, do
profiling for each single program you want to optimize.
Cheers,
Dominique
--
Dominique Michel
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-09-30 20:35 [gentoo-dev] [RFC] CFLAGS paragraph for the GWN Lionel Bouton
2006-09-30 20:58 ` Dominique Michel
@ 2006-09-30 21:48 ` Mike Frysinger
2006-09-30 22:42 ` Lionel Bouton
2006-09-30 21:48 ` Ryan Hill
2006-10-01 0:37 ` [gentoo-dev] " George Prowse
3 siblings, 1 reply; 32+ messages in thread
From: Mike Frysinger @ 2006-09-30 21:48 UTC (permalink / raw
To: gentoo-dev
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On Saturday 30 September 2006 16:35, Lionel Bouton wrote:
> There is a lot of material out there about CFLAGS
`man gcc` always seemed fine to me
in fact, lets read the -ffast-math section:
-ffast-math
This option should never be turned on by any -O option since it can
result in incorrect output for programs which depend on an exact
implementation of IEEE or ISO rules/specifications for math func-
tions.
this flag is never safe to use in CFLAGS
> link='http://gentoo-wiki.com/CFLAGS_matrix'
no way will our documentation link to gentoo-wiki.com
> If possible, I'd like to expand the list of 3.4.6 -> 4.1.1 upgrade
> problems which are linked to experimental CFLAGS
i find maintaining a list of "safe" CFLAGS on a per-gcc basis to be a waste of
time ... but that's just me
-mike
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^ permalink raw reply [flat|nested] 32+ messages in thread
* [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-09-30 20:35 [gentoo-dev] [RFC] CFLAGS paragraph for the GWN Lionel Bouton
2006-09-30 20:58 ` Dominique Michel
2006-09-30 21:48 ` Mike Frysinger
@ 2006-09-30 21:48 ` Ryan Hill
2006-09-30 21:52 ` Robin H. Johnson
2006-10-01 0:37 ` [gentoo-dev] " George Prowse
3 siblings, 1 reply; 32+ messages in thread
From: Ryan Hill @ 2006-09-30 21:48 UTC (permalink / raw
To: gentoo-dev
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Lionel Bouton wrote:
> There are already good resources (http://gentoo-wiki.com/CFLAGS_matrix
> was mentioned to me by robbat2) but they may not be advertised enough.
Most of the info on that page is wrong.
> I'd like to propose a paragraph to the GWN editor which presents some
> gotchas and good references on the subject.
Honestly, the only good reference is the Safe CFLAGS page.
> If possible, I'd like to expand the list of 3.4.6 -> 4.1.1 upgrade
> problems which are linked to experimental CFLAGS. If you want to expand
> the subject to cover other tuning/stability gotchas that recent updates
> might have brought into the light, please feel free to do so. As English
> is not my native tongue, feel free to spell check too.
The english and speeling seem fine.
--de.
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-09-30 21:48 ` Ryan Hill
@ 2006-09-30 21:52 ` Robin H. Johnson
2006-09-30 22:37 ` Ryan Hill
0 siblings, 1 reply; 32+ messages in thread
From: Robin H. Johnson @ 2006-09-30 21:52 UTC (permalink / raw
To: gentoo-dev
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On Sat, Sep 30, 2006 at 03:48:53PM -0600, Ryan Hill wrote:
> Lionel Bouton wrote:
> > There are already good resources (http://gentoo-wiki.com/CFLAGS_matrix
> > was mentioned to me by robbat2) but they may not be advertised enough.
> Most of the info on that page is wrong.
The items on there that note breakages are reasonably correct.
-fvisibility=hidden and -ffast-math DO cause breakages.
-ftree-loop-linear likewise is broken on GCC4.1 last I checked.
> > I'd like to propose a paragraph to the GWN editor which presents some
> > gotchas and good references on the subject.
> Honestly, the only good reference is the Safe CFLAGS page.
The objective here was mainly to point out some things that users are
doing that are causing breakages, leading to bugs that are ultimately
marked INVALID after much tracing.
--
Robin Hugh Johnson
E-Mail : robbat2@gentoo.org
GnuPG FP : 11AC BA4F 4778 E3F6 E4ED F38E B27B 944E 3488 4E85
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^ permalink raw reply [flat|nested] 32+ messages in thread
* [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-09-30 21:52 ` Robin H. Johnson
@ 2006-09-30 22:37 ` Ryan Hill
2006-10-01 0:38 ` Robin H. Johnson
2006-10-01 11:23 ` Duncan
0 siblings, 2 replies; 32+ messages in thread
From: Ryan Hill @ 2006-09-30 22:37 UTC (permalink / raw
To: gentoo-dev
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Robin H. Johnson wrote:
> On Sat, Sep 30, 2006 at 03:48:53PM -0600, Ryan Hill wrote:
>> Lionel Bouton wrote:
>>> There are already good resources (http://gentoo-wiki.com/CFLAGS_matrix
>>> was mentioned to me by robbat2) but they may not be advertised enough.
>> Most of the info on that page is wrong.
> The items on there that note breakages are reasonably correct.
> -fvisibility=hidden and -ffast-math DO cause breakages.
>
> -ftree-loop-linear likewise is broken on GCC4.1 last I checked.
I thought he wanted flags that broke upgrading between GCC 3.4 and 4.1.
tree-loop-linear wasn't in 3.4. If you want flags that just break
stuff with 4.1 you can include -ftree-vectorize.
>>> I'd like to propose a paragraph to the GWN editor which presents some
>>> gotchas and good references on the subject.
>> Honestly, the only good reference is the Safe CFLAGS page.
> The objective here was mainly to point out some things that users are
> doing that are causing breakages, leading to bugs that are ultimately
> marked INVALID after much tracing.
Like using CFLAGS not on the Safe CFLAGS page? ;)
Monsieur Spanky wrote:
> no way will our documentation link to gentoo-wiki.com
It's not documentation, it's the GWN, which has linked to gentoo-wiki
before.
--de.
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-09-30 21:48 ` Mike Frysinger
@ 2006-09-30 22:42 ` Lionel Bouton
2006-09-30 23:27 ` [gentoo-dev] " Ryan Hill
0 siblings, 1 reply; 32+ messages in thread
From: Lionel Bouton @ 2006-09-30 22:42 UTC (permalink / raw
To: gentoo-dev
Mike Frysinger wrote the following on 30.09.2006 23:48 :
> [...]
> `man gcc` always seemed fine to me
>
> in fact, lets read the -ffast-math section:
> -ffast-math
> This option should never be turned on by any -O option since it can
> result in incorrect output for programs which depend on an exact
> implementation of IEEE or ISO rules/specifications for math func-
> tions.
>
> this flag is never safe to use in CFLAGS
>
>
Indeed, I'll add a reminder to adventurous users to check `man gcc` (I
believe I added fast-math following an example somewhere on the web
instead of checking the man page).
>> link='http://gentoo-wiki.com/CFLAGS_matrix'
>>
>
> no way will our documentation link to gentoo-wiki.com
>
>
The GWN paragraph is mainly a 'heads-up' kind of thing, no more. Don't
confuse the GuideXML extract with an official documentation extract, GWN
uses GuideXML too :-)
>> If possible, I'd like to expand the list of 3.4.6 -> 4.1.1 upgrade
>> problems which are linked to experimental CFLAGS
>>
>
> i find maintaining a list of "safe" CFLAGS on a per-gcc basis to be a waste of
> time ... but that's just me
>
That's not the idea. The main idea is to remind people that playing with
CFLAGS is allowed, as long as you remember to revert to safe CFLAGS
before reporting bugs.
As I wasted one dev time by forgetting to check my CFLAGS, I merely
thought that maybe this wasn't a common reflex for other users too
(fast-math was the only unsafe flag I used, I'm pretty conservative and
simply was mistaken because roughly 2 years ago I didn't check the
proper source of information: the man page). Maybe very few bug reports
are caused by inadequate CFLAGS. If my problem is an uncommon exception
I won't press the matter further, there would be no point to do so.
I'll wait and see if other devs are aware of common CFLAGS gotchas
plaguing bugzilla.
Lionel.
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-09-30 22:42 ` Lionel Bouton
@ 2006-09-30 23:27 ` Ryan Hill
0 siblings, 0 replies; 32+ messages in thread
From: Ryan Hill @ 2006-09-30 23:27 UTC (permalink / raw
To: gentoo-dev
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Lionel Bouton wrote:
> I'll wait and see if other devs are aware of common CFLAGS gotchas
> plaguing bugzilla.
Flags such as -fforce-addr and -fweb that change the way registers are
handled can often cause errors when compiling hand-optimised ASM on
architectures with a very limited number of registers (ie. x86). This
turns up a lot in video libraries or graphic processing apps like
ffmpeg, xine-lib, or avidemux.
--de.
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-09-30 20:35 [gentoo-dev] [RFC] CFLAGS paragraph for the GWN Lionel Bouton
` (2 preceding siblings ...)
2006-09-30 21:48 ` Ryan Hill
@ 2006-10-01 0:37 ` George Prowse
3 siblings, 0 replies; 32+ messages in thread
From: George Prowse @ 2006-10-01 0:37 UTC (permalink / raw
To: gentoo-dev
Lionel Bouton wrote:
> Hi, I just had an unpleasant experience with -ffast-math and GCC 4.1.1
> (it borked my LDAP authentication on several systems which worked with
> the same CFLAGS as long as GCC 3.4.6 was used).
>
> There is a lot of material out there about CFLAGS and Gentoo (google
> returns 387000 pages) but what's working for someone might not for
> another. There are flags that work for a GCC version and most ebuilds
> and don't work with another GCC version (my unfortunate experience) or
> some ebuilds. Flag combination/architecture/LDFLAGS might be an issue too.
>
> There are already good resources (http://gentoo-wiki.com/CFLAGS_matrix
> was mentioned to me by robbat2) but they may not be advertised enough.
> I'd like to propose a paragraph to the GWN editor which presents some
> gotchas and good references on the subject.
>
> Here's a draft for review. You're welcomed to expand on the subject.
>
> --- Draft BEGIN ---
> <section>
> <title>CFLAGS</title>
> <body>
>
> <p>
> Being able to tune the CFLAGS is part of one of the core principles of
> Gentoo: let the user be in control. Being in control brings both
> benefits and problems and CFLAGS tuning is not an exception.
> </p>
> <p>
> The recent upgrade to gcc-4.1.1 for x86 and amd64 users changed the
> landscape. Users that spent some time tuning their CFLAGS with gcc-3.4.6
> might find out that an upgrade to gcc-4.1.1 leaves them with an unstable
> system. Example of this are :
> <ul>
> <li>nss_ldap stopped working with -ffast-math</li>
> <li>...</li>
> </ul>
> </p>
> <p>
> Users with unsupported CFLAGS (see the <uri
> link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
> example) might want to return to safe CFLAGS (see <uri
> link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
> updates caused them stability problems. On the other hand, more
> adventurous users might want to experiment with CFLAGS that didn't work
> properly with gcc-3.4.6... As always, the user is in control.
> </p>
> </body>
> </section>
> --- Draft END ---
>
> If possible, I'd like to expand the list of 3.4.6 -> 4.1.1 upgrade
> problems which are linked to experimental CFLAGS. If you want to expand
> the subject to cover other tuning/stability gotchas that recent updates
> might have brought into the light, please feel free to do so. As English
> is not my native tongue, feel free to spell check too.
>
> Cheers,
>
> Lionel.
>
I agree in principle because it would stop people using stupid CFLAGS.
It should have an information section and a "use this CFLAG and dont ask
us for help" section:
<p>
Good Compiler Flag
</p>
<p>
-floop-optimize
Enables safe loop optimisation and is enabled in most -O$
</p>
<p>
Bad Compiler flag
</p>
<p>
Sets |-fno-math-errno|, |-funsafe-math-optimizations|,
|-fno-trapping-math|, |-ffinite-math-only|, |-fno-rounding-math| and
|-fno-signaling-nans|
Used to speed up math functions but causes major b0rkage because it can
result in incorrect output for programs which depend on an exact
implementation of IEEE or ISO rules/specifications for math functions.
Use this and dont bother asking for help.
</p>
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-09-30 22:37 ` Ryan Hill
@ 2006-10-01 0:38 ` Robin H. Johnson
2006-10-01 11:23 ` Duncan
1 sibling, 0 replies; 32+ messages in thread
From: Robin H. Johnson @ 2006-10-01 0:38 UTC (permalink / raw
To: gentoo-dev
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On Sat, Sep 30, 2006 at 04:37:05PM -0600, Ryan Hill wrote:
> I thought he wanted flags that broke upgrading between GCC 3.4 and 4.1.
> tree-loop-linear wasn't in 3.4. If you want flags that just break
> stuff with 4.1 you can include -ftree-vectorize.
Thanks.
> > The objective here was mainly to point out some things that users are
> > doing that are causing breakages, leading to bugs that are ultimately
> > marked INVALID after much tracing.
> Like using CFLAGS not on the Safe CFLAGS page? ;)
Not really.
One needs to use some common sense as a developer in evaluating user
CFLAGS - because there are plenty of flags that are safe, but aren't
listed on that page.
Several years ago, I wrote a package that was the forerunner of the
'Safe CFLAGS' page - genflags. It was close to unmaintable at the time
however, so it's suffered a lot of bit-rot. With the advent of
libcpuinfo, and x86info being written, it stands a much better chance of
giving useful output, but that still does not supersede the common sense
statement above.
--
Robin Hugh Johnson
E-Mail : robbat2@gentoo.org
GnuPG FP : 11AC BA4F 4778 E3F6 E4ED F38E B27B 944E 3488 4E85
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^ permalink raw reply [flat|nested] 32+ messages in thread
* [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-09-30 22:37 ` Ryan Hill
2006-10-01 0:38 ` Robin H. Johnson
@ 2006-10-01 11:23 ` Duncan
2006-10-01 16:49 ` Donnie Berkholz
` (2 more replies)
1 sibling, 3 replies; 32+ messages in thread
From: Duncan @ 2006-10-01 11:23 UTC (permalink / raw
To: gentoo-dev
Ryan Hill <dirtyepic.sk@gmail.com> posted efmrae$jff$1@sea.gmane.org,
excerpted below, on Sat, 30 Sep 2006 16:37:05 -0600:
> If you want flags that just break
> stuff with 4.1 you can include -ftree-vectorize.
Could you point me at some info on this one (-ftree-vectorize)? It came
up on the amd64 list a week or so ago, when someone asked what I thought
of it and why I didn't have it in my cflags (which I had just explained).
I said I didn't know enough about it to make a case either way, and as
such, didn't choose to use it. However, after a bit of discussion, I
decided to add it to my cflags on a very experimental basis. I haven't
experienced any issues with it, but then I haven't done any major
compiling since then either, only the routine updates.
If I had rather more info on it, therefore, particularly on why it might
break stuff, I'd be able to pass it on, telling the list and in particular
the guy that asked, why it's NOT a good thing to use. Thus, point me at
it, if you got it. Even something as simple as a list of bugs traced to
it would be useful as something I could point at, if that's what you are
basing your remark on.
Or does the problem not necessarily apply to amd64? Even knowing that
would be useful. I simply don't know anything much at all about it, beyond
a generally vague idea that it means using mmx/sse/whatever vector
instructions to parallelize loops.
TIA.
--
Duncan - List replies preferred. No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master." Richard Stallman
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-10-01 11:23 ` Duncan
@ 2006-10-01 16:49 ` Donnie Berkholz
2006-10-01 17:02 ` Diego 'Flameeyes' Pettenò
2006-10-01 18:00 ` Ryan Hill
2006-10-01 21:01 ` Jeroen Roovers
2 siblings, 1 reply; 32+ messages in thread
From: Donnie Berkholz @ 2006-10-01 16:49 UTC (permalink / raw
To: gentoo-dev
Duncan wrote:
> Could you point me at some info on this one (-ftree-vectorize)? It came
> up on the amd64 list a week or so ago, when someone asked what I thought
> of it and why I didn't have it in my cflags (which I had just explained).
> I said I didn't know enough about it to make a case either way, and as
> such, didn't choose to use it. However, after a bit of discussion, I
> decided to add it to my cflags on a very experimental basis. I haven't
> experienced any issues with it, but then I haven't done any major
> compiling since then either, only the routine updates.
>
> If I had rather more info on it, therefore, particularly on why it might
> break stuff, I'd be able to pass it on, telling the list and in particular
> the guy that asked, why it's NOT a good thing to use. Thus, point me at
> it, if you got it. Even something as simple as a list of bugs traced to
> it would be useful as something I could point at, if that's what you are
> basing your remark on.
I can't give you reasons, but I can tell you it totally broke my x86
system a while back.
Thanks,
Donnie
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-10-01 16:49 ` Donnie Berkholz
@ 2006-10-01 17:02 ` Diego 'Flameeyes' Pettenò
0 siblings, 0 replies; 32+ messages in thread
From: Diego 'Flameeyes' Pettenò @ 2006-10-01 17:02 UTC (permalink / raw
To: gentoo-dev
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On Sunday 01 October 2006 18:49, Donnie Berkholz wrote:
> I can't give you reasons, but I can tell you it totally broke my x86
> system a while back.
-ftree-vectorize on x86 and PowerPC is known to create broken executables
(when it comes to actually create the executable).
I'm using it on AMD64 fine since 4.0 pre-releases though (suggested for the
daredevils by Halcy0n iirc), and never had problems with it.
Most likely this is due either to the usual limitations of x86 (registers,
PIC, 387 fpmath), or to not be able to ensure the availability of extra
instructions on x86.
--
Diego "Flameeyes" Pettenò - http://farragut.flameeyes.is-a-geek.org/
Gentoo/Alt lead, Gentoo/FreeBSD, Video, AMD64, Sound, PAM, KDE
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^ permalink raw reply [flat|nested] 32+ messages in thread
* [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-10-01 11:23 ` Duncan
2006-10-01 16:49 ` Donnie Berkholz
@ 2006-10-01 18:00 ` Ryan Hill
2006-10-02 10:40 ` Duncan
2006-10-01 21:01 ` Jeroen Roovers
2 siblings, 1 reply; 32+ messages in thread
From: Ryan Hill @ 2006-10-01 18:00 UTC (permalink / raw
To: gentoo-dev
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Duncan wrote:
> Could you point me at some info on this one (-ftree-vectorize)? It came
> up on the amd64 list a week or so ago, when someone asked what I thought
> of it and why I didn't have it in my cflags (which I had just explained).
> I said I didn't know enough about it to make a case either way, and as
> such, didn't choose to use it. However, after a bit of discussion, I
> decided to add it to my cflags on a very experimental basis. I haven't
> experienced any issues with it, but then I haven't done any major
> compiling since then either, only the routine updates.
http://tinyurl.com/l75we
They've fixed quite a few of the ICE's since last I looked, though
there's more than a couple that went in after 4.1.1. 4.2 is a little
better, but I'm having enough trouble getting it to build things
properly _without_ using any fancy flags right now. ;p
See http://tinyurl.com/rt3aa for some real-world examples.
> Or does the problem not necessarily apply to amd64? Even knowing that
> would be useful. I simply don't know anything much at all about it, beyond
> a generally vague idea that it means using mmx/sse/whatever vector
> instructions to parallelize loops.
I'd say that there's more ICE's on i686-pc-linux-gnu than
x86_64-*-linux-gnu, but there's still enough. Luckily Halcy0n was
really good for reducing testcases and pushing them upstream, so a lot
of these issues got fixed at the source.
--de.
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-10-01 11:23 ` Duncan
2006-10-01 16:49 ` Donnie Berkholz
2006-10-01 18:00 ` Ryan Hill
@ 2006-10-01 21:01 ` Jeroen Roovers
2 siblings, 0 replies; 32+ messages in thread
From: Jeroen Roovers @ 2006-10-01 21:01 UTC (permalink / raw
To: gentoo-dev
On Sun, 1 Oct 2006 11:23:37 +0000 (UTC)
"Duncan" <1i5t5.duncan@cox.net> wrote:
> Ryan Hill <dirtyepic.sk@gmail.com> posted efmrae$jff$1@sea.gmane.org,
> excerpted below, on Sat, 30 Sep 2006 16:37:05 -0600:
>
> > If you want flags that just break
> > stuff with 4.1 you can include -ftree-vectorize.
>
> Could you point me at some info on this one (-ftree-vectorize)?
> SNIP!!!!1one <
-ftree-vectorize replaces the already deprecated -fentmoot, which is of course a Really Old option for GCC where all code is blown up in memory and then parsed and spit out in as many different ways as possible to ultimately come to the best most very optimised way to say the simplest things. It is wise to also use -Woverly-longwinded in this case, so all the optimisation steps are written verbosely to stderr interspersed with funny anecdotal evidence of extraneously confablucious witticisms (to stdout, naturally).[1]
Kind regards,
JeR
[1] -fentmoot got the chop from one of the Wizards of Yore who is known by many as Saruman the Black and White Water-Loving Bird, and the rest is History.
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* [gentoo-dev] Re: [RFC] CFLAGS paragraph for the GWN
2006-10-01 18:00 ` Ryan Hill
@ 2006-10-02 10:40 ` Duncan
0 siblings, 0 replies; 32+ messages in thread
From: Duncan @ 2006-10-02 10:40 UTC (permalink / raw
To: gentoo-dev
Ryan Hill <dirtyepic.sk@gmail.com> posted efovnn$sm8$1@sea.gmane.org,
excerpted below, on Sun, 01 Oct 2006 12:00:10 -0600:
> Duncan wrote:
>
>> Could you point me at some info on this one (-ftree-vectorize)?
>
> http://tinyurl.com/l75we
>
> They've fixed quite a few [...]
>
> See http://tinyurl.com/rt3aa for some real-world examples.
>
>> Or does the problem not necessarily apply to amd64?
>
> I'd say that there's more ICE's on i686-pc-linux-gnu than
> x86_64-*-linux-gnu, but there's still enough. Luckily Halcy0n was
> really good [...]
Thanks! Saving and forwarding the gist to the amd64 list, where I'm sure
others will find it useful as well.
--
Duncan - List replies preferred. No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master." Richard Stallman
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
@ 2006-10-03 0:56 Lionel Bouton
2006-10-03 11:55 ` Chris Gianelloni
` (2 more replies)
0 siblings, 3 replies; 32+ messages in thread
From: Lionel Bouton @ 2006-10-03 0:56 UTC (permalink / raw
To: gentoo-dev
Here's an updated draft. I included most of your remarks and added some
notes on append-flags/filter-flags. I'll probably submit it to Ulrich
around the end of the week.
--- Draft BEGIN ---
<section>
<title>CFLAGS</title>
<body>
<p>
Being able to tune the CFLAGS is part of one of the core principles of
Gentoo: let the user be in control. Being in control brings both
benefits and problems and CFLAGS tuning is not an exception.
</p>
<p>
The recent upgrade to gcc-4.1.1 for x86 and amd64 users changed the
landscape. Users that spent some time tuning their CFLAGS with gcc-3.4.6
might find out that an upgrade to gcc-4.1.1 leaves them with an unstable
system. Example of this are :
<ul>
<li>nss_ldap stopped working with <c>-ffast-math</c> (reported to break
many packages changing with the actual gcc version)</li>
<li><c>-fvisibility-inlines-hidden</c> still breaks some code</li>
<li>if you used gcc-4.0, <c>-ftree-loop-linear</c> now breaks in
gcc-4.1(at least with mesa)</li>
<li>again for gcc-4.0 users, <c>-ftree-vectorize</c> is known to be
broken in gcc-4.1 (at least for x86 and ppc, amd64 users seem to be
safe)</li>
<li><c>-fforce-addr</c> and <c>-fweb</c> break regularly on x86 with
video libraries or graphic processing apps which use hand-optimised ASM</li>
</ul>
</p>
<p>
Users with unsupported CFLAGS (see the <uri
link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
example) might want to return to safe CFLAGS (see <uri
link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
updates caused them stability problems. On the other hand, more
adventurous users might want to experiment with CFLAGS that didn't work
properly with gcc-3.4.6... As always, the user is in control.
</p>
<p>
Notes:
<ul>
<li>The gcc man page contains warnings for some unsafe optimization
options. You should read it carefully when you experiment with CFLAGS or
upgrade GCC on a CFLAGS-customized Gentoo.</li>
<li>Some options that are unsafe in the system-wide CFLAGS might be
added automatically in some ebuilds if the developper deems them safe
(by redefining CFLAGS or using append-flags of the flag-o-matic eclass).
For example <c>-ffast-math</c> is added by the xmame/xmess ebuilds on
most architectures even if you don't put it in your CFLAGS.</li>
<li>You might get an idea of the stability issues of a specific
optimization option by running: <c>find /usr/portage -name '*.ebuild'|
xargs grep -- '-<your-risky-optimization-option>'</c>. It takes quite
some time, but might be enlightening: look for the 'filter-flags'.</li>
</ul>
</p>
</body>
</section>
--- Draft END ---
Lionel
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 0:56 Lionel Bouton
@ 2006-10-03 11:55 ` Chris Gianelloni
2006-10-03 12:26 ` Ciaran McCreesh
2006-10-03 16:11 ` Josh Saddler
2 siblings, 0 replies; 32+ messages in thread
From: Chris Gianelloni @ 2006-10-03 11:55 UTC (permalink / raw
To: gentoo-dev
[-- Attachment #1: Type: text/plain, Size: 3228 bytes --]
On Tue, 2006-10-03 at 02:56 +0200, Lionel Bouton wrote:
> Here's an updated draft. I included most of your remarks and added some
> notes on append-flags/filter-flags. I'll probably submit it to Ulrich
> around the end of the week.
I surely hope you don't submit it to Ulrich if you want it to actually
ever get in the GWN. Instead, you should submit it to
gwn-feedback@gentoo.org like the GWN tells you to do.
=]
Thanks,
> --- Draft BEGIN ---
> <section>
> <title>CFLAGS</title>
> <body>
>
> <p>
> Being able to tune the CFLAGS is part of one of the core principles of
> Gentoo: let the user be in control. Being in control brings both
> benefits and problems and CFLAGS tuning is not an exception.
> </p>
> <p>
> The recent upgrade to gcc-4.1.1 for x86 and amd64 users changed the
> landscape. Users that spent some time tuning their CFLAGS with gcc-3.4.6
> might find out that an upgrade to gcc-4.1.1 leaves them with an unstable
> system. Example of this are :
> <ul>
> <li>nss_ldap stopped working with <c>-ffast-math</c> (reported to break
> many packages changing with the actual gcc version)</li>
> <li><c>-fvisibility-inlines-hidden</c> still breaks some code</li>
> <li>if you used gcc-4.0, <c>-ftree-loop-linear</c> now breaks in
> gcc-4.1(at least with mesa)</li>
> <li>again for gcc-4.0 users, <c>-ftree-vectorize</c> is known to be
> broken in gcc-4.1 (at least for x86 and ppc, amd64 users seem to be
> safe)</li>
> <li><c>-fforce-addr</c> and <c>-fweb</c> break regularly on x86 with
> video libraries or graphic processing apps which use hand-optimised ASM</li>
> </ul>
> </p>
> <p>
> Users with unsupported CFLAGS (see the <uri
> link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
> example) might want to return to safe CFLAGS (see <uri
> link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
> updates caused them stability problems. On the other hand, more
> adventurous users might want to experiment with CFLAGS that didn't work
> properly with gcc-3.4.6... As always, the user is in control.
> </p>
> <p>
> Notes:
> <ul>
> <li>The gcc man page contains warnings for some unsafe optimization
> options. You should read it carefully when you experiment with CFLAGS or
> upgrade GCC on a CFLAGS-customized Gentoo.</li>
> <li>Some options that are unsafe in the system-wide CFLAGS might be
> added automatically in some ebuilds if the developper deems them safe
> (by redefining CFLAGS or using append-flags of the flag-o-matic eclass).
> For example <c>-ffast-math</c> is added by the xmame/xmess ebuilds on
> most architectures even if you don't put it in your CFLAGS.</li>
> <li>You might get an idea of the stability issues of a specific
> optimization option by running: <c>find /usr/portage -name '*.ebuild'|
> xargs grep -- '-<your-risky-optimization-option>'</c>. It takes quite
> some time, but might be enlightening: look for the 'filter-flags'.</li>
> </ul>
> </p>
> </body>
> </section>
> --- Draft END ---
>
> Lionel
--
Chris Gianelloni
Release Engineering Strategic Lead
Alpha/AMD64/x86 Architecture Teams
Games Developer/Council Member/Foundation Trustee
Gentoo Foundation
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 0:56 Lionel Bouton
2006-10-03 11:55 ` Chris Gianelloni
@ 2006-10-03 12:26 ` Ciaran McCreesh
2006-10-03 13:15 ` Mike Frysinger
2006-10-03 22:37 ` Lionel Bouton
2006-10-03 16:11 ` Josh Saddler
2 siblings, 2 replies; 32+ messages in thread
From: Ciaran McCreesh @ 2006-10-03 12:26 UTC (permalink / raw
To: gentoo-dev
[-- Attachment #1: Type: text/plain, Size: 2467 bytes --]
On Tue, 03 Oct 2006 02:56:42 +0200 Lionel Bouton
<lionel-dev@bouton.name> wrote:
| Being able to tune the CFLAGS is part of one of the core principles of
| Gentoo: let the user be in control.
What? No it isn't.
| <li>nss_ldap stopped working with <c>-ffast-math</c> (reported to
| break many packages changing with the actual gcc version)</li>
Uh, -ffast-math has never been and will never be a safe thing to stick
in CFLAGS.
| <li><c>-fvisibility-inlines-hidden</c> still breaks some code</li>
Ditto. In C++, inlining is a *guideline* that the compiler can and will
ignore as it sees fit. Only code specifically designed to use this flag
should specify it, and even then it can still lead to failures because
of the non-guaranteed nature of inlining.
| <li>if you used gcc-4.0, <c>-ftree-loop-linear</c> now breaks in
| gcc-4.1(at least with mesa)</li>
Users shouldn't be sticking that in CFLAGS anyway.
| <li>again for gcc-4.0 users, <c>-ftree-vectorize</c> is known to be
| broken in gcc-4.1 (at least for x86 and ppc, amd64 users seem to be
| safe)</li>
Or that.
| <li><c>-fforce-addr</c> and <c>-fweb</c> break regularly on x86 with
| video libraries or graphic processing apps which use hand-optimised
| ASM</li> </ul>
Or that.
| Users with unsupported CFLAGS (see the <uri
| link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
| example) might want to return to safe CFLAGS (see <uri
| link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
| updates caused them stability problems. On the other hand, more
| adventurous users might want to experiment with CFLAGS that didn't
| work properly with gcc-3.4.6... As always, the user is in control.
Linking to that is a very bad idea. The wiki is in control of the
minority ricer fringe.
GWN shouldn't be advocating this kind of thing at all. Here's a better
paragraph:
<p>We would like to remind you that using anything beyond -O2
-fomit-frame-pointer -march/-mcpu/-mtune in CFLAGS or CXXLFAGS (and
-mieee, -mabi etc on selected archs that tell you to do this), and using
anything at all in LDFLAGS or ASFLAGS, is pointless and will lead to a
broken system. Your penis length is not proportional to the size of your
CFLAGS.</p>
--
Ciaran McCreesh
Mail : ciaranm at ciaranm.org
Web : http://ciaranm.org/
as-needed is broken : http://ciaranm.org/show_post.pl?post_id=13
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 12:26 ` Ciaran McCreesh
@ 2006-10-03 13:15 ` Mike Frysinger
2006-10-04 8:35 ` Jan Kundrát
2006-10-03 22:37 ` Lionel Bouton
1 sibling, 1 reply; 32+ messages in thread
From: Mike Frysinger @ 2006-10-03 13:15 UTC (permalink / raw
To: gentoo-dev
[-- Attachment #1: Type: text/plain, Size: 197 bytes --]
On Tuesday 03 October 2006 08:26, Ciaran McCreesh wrote:
> Your penis length is not proportional to the size of your CFLAGS.
i could update vpenis.sh so that this statement is incorrect ...
-mike
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 0:56 Lionel Bouton
2006-10-03 11:55 ` Chris Gianelloni
2006-10-03 12:26 ` Ciaran McCreesh
@ 2006-10-03 16:11 ` Josh Saddler
2006-10-03 17:16 ` Lionel Bouton
2 siblings, 1 reply; 32+ messages in thread
From: Josh Saddler @ 2006-10-03 16:11 UTC (permalink / raw
To: gentoo-dev
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Lionel Bouton wrote:
> Here's an updated draft. I included most of your remarks and added some
> notes on append-flags/filter-flags. I'll probably submit it to Ulrich
> around the end of the week.
>
> --- Draft BEGIN ---
> <section>
> <title>CFLAGS</title>
> <body>
>
> <p>
> Being able to tune the CFLAGS is part of one of the core principles of
> Gentoo: let the user be in control. Being in control brings both
> benefits and problems and CFLAGS tuning is not an exception.
> </p>
> <p>
> The recent upgrade to gcc-4.1.1 for x86 and amd64 users changed the
> landscape. Users that spent some time tuning their CFLAGS with gcc-3.4.6
> might find out that an upgrade to gcc-4.1.1 leaves them with an unstable
> system. Example of this are :
> <ul>
> <li>nss_ldap stopped working with <c>-ffast-math</c> (reported to break
> many packages changing with the actual gcc version)</li>
> <li><c>-fvisibility-inlines-hidden</c> still breaks some code</li>
> <li>if you used gcc-4.0, <c>-ftree-loop-linear</c> now breaks in
> gcc-4.1(at least with mesa)</li>
> <li>again for gcc-4.0 users, <c>-ftree-vectorize</c> is known to be
> broken in gcc-4.1 (at least for x86 and ppc, amd64 users seem to be
> safe)</li>
> <li><c>-fforce-addr</c> and <c>-fweb</c> break regularly on x86 with
> video libraries or graphic processing apps which use hand-optimised ASM</li>
> </ul>
> </p>
> <p>
> Users with unsupported CFLAGS (see the <uri
> link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
> example) might want to return to safe CFLAGS (see <uri
> link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
> updates caused them stability problems. On the other hand, more
> adventurous users might want to experiment with CFLAGS that didn't work
> properly with gcc-3.4.6... As always, the user is in control.
> </p>
> <p>
> Notes:
> <ul>
> <li>The gcc man page contains warnings for some unsafe optimization
> options. You should read it carefully when you experiment with CFLAGS or
> upgrade GCC on a CFLAGS-customized Gentoo.</li>
> <li>Some options that are unsafe in the system-wide CFLAGS might be
> added automatically in some ebuilds if the developper deems them safe
> (by redefining CFLAGS or using append-flags of the flag-o-matic eclass).
> For example <c>-ffast-math</c> is added by the xmame/xmess ebuilds on
> most architectures even if you don't put it in your CFLAGS.</li>
> <li>You might get an idea of the stability issues of a specific
> optimization option by running: <c>find /usr/portage -name '*.ebuild'|
> xargs grep -- '-<your-risky-optimization-option>'</c>. It takes quite
> some time, but might be enlightening: look for the 'filter-flags'.</li>
> </ul>
> </p>
> </body>
> </section>
> --- Draft END ---
>
> Lionel
Uh, Gentoo-wiki does not get linked. Period. Not in official Gentoo stuff -- the
wiki is not supported or endorsed by the developers. It's not remotely official,
and in fact contains a great deal of false and/or misleading information, which
is why you don't see it mentioned in any documentation (for example).
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--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 16:11 ` Josh Saddler
@ 2006-10-03 17:16 ` Lionel Bouton
2006-10-03 17:22 ` Daniel Ostrow
0 siblings, 1 reply; 32+ messages in thread
From: Lionel Bouton @ 2006-10-03 17:16 UTC (permalink / raw
To: gentoo-dev
Josh Saddler wrote the following on 03.10.2006 18:11 :
> (...)
> > Lionel
> Uh, Gentoo-wiki does not get linked.
Are there many trying to link to the Gentoo Wiki in official
documentation? It seems guns are warm and devs quick to jump to
conclusions (re-read the title and the previous discussion on this very
subject) :-) Keep cool, I agree with your statement (for numerous
reasons), it's just out of context: I propose a 'reminder' chapter for
the GWN, that's all.
Lionel.
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 17:16 ` Lionel Bouton
@ 2006-10-03 17:22 ` Daniel Ostrow
2006-10-03 17:47 ` Charlie
` (2 more replies)
0 siblings, 3 replies; 32+ messages in thread
From: Daniel Ostrow @ 2006-10-03 17:22 UTC (permalink / raw
To: gentoo-dev
[-- Attachment #1: Type: text/plain, Size: 920 bytes --]
On Tue, 2006-10-03 at 19:16 +0200, Lionel Bouton wrote:
> Josh Saddler wrote the following on 03.10.2006 18:11 :
> > (...)
> > > Lionel
> > Uh, Gentoo-wiki does not get linked.
>
> Are there many trying to link to the Gentoo Wiki in official
> documentation? It seems guns are warm and devs quick to jump to
> conclusions (re-read the title and the previous discussion on this very
> subject) :-) Keep cool, I agree with your statement (for numerous
> reasons), it's just out of context: I propose a 'reminder' chapter for
> the GWN, that's all.
Ok...lets try this...
Gentoo-wiki does not now nor will it ever get linked to from official
Gentoo media, documentation, or anything else within the www.gentoo.org
namespace...
It is inherently unreliable and outside of Gentoo's control. It will eat
your dog, kill your cat, club baby seals and make the hole in the O-Zone
layer bigger...
--Dan
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 17:22 ` Daniel Ostrow
@ 2006-10-03 17:47 ` Charlie
2006-10-03 17:56 ` Stephen P. Becker
2006-10-03 17:49 ` Lionel Bouton
2006-10-03 18:08 ` Simon Stelling
2 siblings, 1 reply; 32+ messages in thread
From: Charlie @ 2006-10-03 17:47 UTC (permalink / raw
To: gentoo-dev
On 03/10/06, Daniel Ostrow <dostrow@gentoo.org> wrote:
> Gentoo-wiki does not now nor will it ever get linked to from official
> Gentoo media, documentation, or anything else within the www.gentoo.org
> namespace...
http://sources.gentoo.org/viewcvs.py/gentoo-x86/app-emulation/xen/xen-3.0.2.ebuild?rev=1.6
See pkg_postinst :P
--
Charlie
--
gentoo-dev@gentoo.org mailing list
^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 17:22 ` Daniel Ostrow
2006-10-03 17:47 ` Charlie
@ 2006-10-03 17:49 ` Lionel Bouton
2006-10-03 20:46 ` Chris Gianelloni
2006-10-03 18:08 ` Simon Stelling
2 siblings, 1 reply; 32+ messages in thread
From: Lionel Bouton @ 2006-10-03 17:49 UTC (permalink / raw
To: gentoo-dev
Daniel Ostrow wrote the following on 03.10.2006 19:22 :
>
> Ok...lets try this...
>
> Gentoo-wiki does not now nor will it ever get linked to from official
> Gentoo media, documentation, or anything else within the www.gentoo.org
> namespace...
>
>
It seemed to me that although it is hosted in the www.gentoo.org space
the GWN isn't official Gentoo stuff.
Plus : http://www.gentoo.org/news/en/gwn/20060424-newsletter.xml
I can understand the problem with linking to the Wiki but I believe this
source of information is not too bad, considered what google returns for
gentoo cflags.
> It is inherently unreliable and outside of Gentoo's control. It will eat
> your dog, kill your cat, club baby seals and make the hole in the O-Zone
> layer bigger...
>
I can add a reminder that this is unofficial stuff if it's important to
devs, but as stated above I believed content in the GWN should be
approved by the GWN people not devs (I remember there were discussions
of making GWN official, but I believe it isn't yet). Feel free to sched
more light on this for me.
Lionel.
--
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 17:47 ` Charlie
@ 2006-10-03 17:56 ` Stephen P. Becker
0 siblings, 0 replies; 32+ messages in thread
From: Stephen P. Becker @ 2006-10-03 17:56 UTC (permalink / raw
To: gentoo-dev
Charlie wrote:
> On 03/10/06, Daniel Ostrow <dostrow@gentoo.org> wrote:
>> Gentoo-wiki does not now nor will it ever get linked to from official
>> Gentoo media, documentation, or anything else within the www.gentoo.org
>> namespace...
>
> http://sources.gentoo.org/viewcvs.py/gentoo-x86/app-emulation/xen/xen-3.0.2.ebuild?rev=1.6
>
> See pkg_postinst :P
>
That's a QA bug that needs to be filed...
-Steve
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* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 17:22 ` Daniel Ostrow
2006-10-03 17:47 ` Charlie
2006-10-03 17:49 ` Lionel Bouton
@ 2006-10-03 18:08 ` Simon Stelling
2 siblings, 0 replies; 32+ messages in thread
From: Simon Stelling @ 2006-10-03 18:08 UTC (permalink / raw
To: gentoo-dev
Daniel Ostrow wrote:
> It is inherently unreliable and outside of Gentoo's control.
Sorry, I really tried hard, but I just couldn't anymore... Must... say...
_ _ _ _ _ ____ ____ _ ____ _____
/ \ | | | | | | | | _ \ | __ ) / \ / ___|| ____|
/ _ \ | | | | | | | | |_) | | _ \ / _ \ \___ \| _|
/ ___ \| |___| |___ | |_| | _ < | |_) / ___ \ ___) | |___
/_/ \_\_____|_____| \___/|_| \_\ |____/_/ \_\____/|_____|
_ ____ _____ ____ _____ _ ___ _ _ ____ _____ ___
/ \ | _ \| ____| | __ )| ____| | / _ \| \ | |/ ___| |_ _/ _ \
/ _ \ | |_) | _| | _ \| _| | | | | | | \| | | _ | || | | |
/ ___ \| _ <| |___ | |_) | |___| |__| |_| | |\ | |_| | | || |_| |
/_/ \_\_| \_\_____| |____/|_____|_____\___/|_| \_|\____| |_| \___/
_ _ ____
| | | / ___|
| | | \___ \
| |_| |___) |
\___/|____/
--
Kind Regards,
Simon Stelling
Gentoo/AMD64 developer
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 17:49 ` Lionel Bouton
@ 2006-10-03 20:46 ` Chris Gianelloni
2006-10-03 22:14 ` Lionel Bouton
0 siblings, 1 reply; 32+ messages in thread
From: Chris Gianelloni @ 2006-10-03 20:46 UTC (permalink / raw
To: gentoo-dev
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On Tue, 2006-10-03 at 19:49 +0200, Lionel Bouton wrote:
> It seemed to me that although it is hosted in the www.gentoo.org space
> the GWN isn't official Gentoo stuff.
The GWN is staffed entirely by developers. We have non-developer
writers, but the staffers are all developers.
To be honest, rather than providing links to an external resource that
may or may not be correct, and may be changed at any time by anyone, I
would much prefer to duplicate the information in the GWN itself.
--
Chris Gianelloni
Release Engineering Strategic Lead
Alpha/AMD64/x86 Architecture Teams
Games Developer/Council Member/Foundation Trustee
Gentoo Foundation
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 20:46 ` Chris Gianelloni
@ 2006-10-03 22:14 ` Lionel Bouton
0 siblings, 0 replies; 32+ messages in thread
From: Lionel Bouton @ 2006-10-03 22:14 UTC (permalink / raw
To: gentoo-dev
Chris Gianelloni wrote the following on 03.10.2006 22:46 :
> On Tue, 2006-10-03 at 19:49 +0200, Lionel Bouton wrote:
>
>> It seemed to me that although it is hosted in the www.gentoo.org space
>> the GWN isn't official Gentoo stuff.
>>
>
> The GWN is staffed entirely by developers. We have non-developer
> writers, but the staffers are all developers.
>
> To be honest, rather than providing links to an external resource that
> may or may not be correct, and may be changed at any time by anyone, I
> would much prefer to duplicate the information in the GWN itself.
>
Thats fine with me. It may be a bit too long as is so I'll update my
draft trying to make things short and let you point out errors in the
result (this was the main idea of bringing the draft on this list: use
the devs' experience to bring new content and filter out errors).
Thanks for the heads up.
Lionel
PS: I was worried that GuideXML might be a little unreadable, but
apparently everyone here has an xsltproc ready to run in their brain :-)
so I'll go on with it.
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* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 12:26 ` Ciaran McCreesh
2006-10-03 13:15 ` Mike Frysinger
@ 2006-10-03 22:37 ` Lionel Bouton
2006-10-04 12:25 ` Paul de Vrieze
1 sibling, 1 reply; 32+ messages in thread
From: Lionel Bouton @ 2006-10-03 22:37 UTC (permalink / raw
To: gentoo-dev
Ciaran McCreesh wrote the following on 03.10.2006 14:26 :
> On Tue, 03 Oct 2006 02:56:42 +0200 Lionel Bouton
> <lionel-dev@bouton.name> wrote:
> | Being able to tune the CFLAGS is part of one of the core principles of
> | Gentoo: let the user be in control.
>
> What? No it isn't.
>
Maybe it depends on what you mean by 'in control'. What I mean is that
you have a good stable base from which to work on, but nothing prevents
you to tweak things like you want: Gentoo doesn't get in your way.
http://www.gentoo.org/main/en/about.xml mentions "Extreme
Configurabiliy" and the main picture states "Larry the Cow was in
control. And he liked it.".
> | <li>nss_ldap stopped working with <c>-ffast-math</c> (reported to
> | break many packages changing with the actual gcc version)</li>
>
> Uh, -ffast-math has never been and will never be a safe thing to stick
> in CFLAGS.
>
I agree (how could I say otherwise after spending several days with a
hole in my foot finally finding that I had a gun named fast-math in my
hand :-) ).
Apparently many developpers think that it might be in CFLAGS though (see
the amount of 'filter-flags -ffast-math' in ebuilds) so a reminder might
not be wasted for some users.
>
> | Users with unsupported CFLAGS (see the <uri
> | link='http://gentoo-wiki.com/CFLAGS_matrix'>CFLAGS matrix</uri> for
> | example) might want to return to safe CFLAGS (see <uri
> | link='http://gentoo-wiki.com/Safe_Cflags'>Safe CFLAGS</uri>) if recent
> | updates caused them stability problems. On the other hand, more
> | adventurous users might want to experiment with CFLAGS that didn't
> | work properly with gcc-3.4.6... As always, the user is in control.
>
> Linking to that is a very bad idea. The wiki is in control of the
> minority ricer fringe.
>
>
Ok. Anyway I'm now convinced that a dev-proofed version of its content
in the GWN would be far better.
> GWN shouldn't be advocating this kind of thing at all. Here's a better
> paragraph:
>
> <p>We would like to remind you that using anything beyond -O2
> -fomit-frame-pointer -march/-mcpu/-mtune in CFLAGS or CXXLFAGS (and
> -mieee, -mabi etc on selected archs that tell you to do this), and using
> anything at all in LDFLAGS or ASFLAGS, is pointless and will lead to a
> broken system. Your penis length is not proportional to the size of your
> CFLAGS.</p>
>
>
Hum, I'll leave out the last sentence or rephrase it... I'd prefer to be
more soft-spoken: pointless might be a little too much too. Let's say
that the cost-risk/benefit ratio is not worth it for the vast majority
of users. CFLAGS tuning should probably only be used by people with very
specific needs (gcc devs/testers, HPTC people with extensive
knowledge/experience of the problems involved). For LDFLAGS and ASFLAGS
I'll take your word for it (I never even tried modifying them myself).
Lionel.
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* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 13:15 ` Mike Frysinger
@ 2006-10-04 8:35 ` Jan Kundrát
0 siblings, 0 replies; 32+ messages in thread
From: Jan Kundrát @ 2006-10-04 8:35 UTC (permalink / raw
To: gentoo-dev
[-- Attachment #1: Type: text/plain, Size: 172 bytes --]
Mike Frysinger wrote:
> i could update vpenis.sh so that this statement is incorrect ...
Please go for it :)
-jkt
--
cd /local/pub && more beer > /dev/mouth
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^ permalink raw reply [flat|nested] 32+ messages in thread
* Re: [gentoo-dev] [RFC] CFLAGS paragraph for the GWN
2006-10-03 22:37 ` Lionel Bouton
@ 2006-10-04 12:25 ` Paul de Vrieze
0 siblings, 0 replies; 32+ messages in thread
From: Paul de Vrieze @ 2006-10-04 12:25 UTC (permalink / raw
To: gentoo-dev
>
> Maybe it depends on what you mean by 'in control'. What I mean is that
> you have a good stable base from which to work on, but nothing prevents
> you to tweak things like you want: Gentoo doesn't get in your way.
> http://www.gentoo.org/main/en/about.xml mentions "Extreme
> Configurabiliy" and the main picture states "Larry the Cow was in
> control. And he liked it.".
>
It certainly is, but if you do something against the developers advice
there is a simple rule: If it breaks you get to keep the pieces.
>
> I agree (how could I say otherwise after spending several days with a
> hole in my foot finally finding that I had a gun named fast-math in my
> hand :-) ).
> Apparently many developpers think that it might be in CFLAGS though (see
> the amount of 'filter-flags -ffast-math' in ebuilds) so a reminder might
> not be wasted for some users.
Those ebuilds should be changed to die instead of filtering. -ffast-math
is just stupid to enable globally.
Paul
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end of thread, other threads:[~2006-10-04 12:29 UTC | newest]
Thread overview: 32+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-09-30 20:35 [gentoo-dev] [RFC] CFLAGS paragraph for the GWN Lionel Bouton
2006-09-30 20:58 ` Dominique Michel
2006-09-30 21:48 ` Mike Frysinger
2006-09-30 22:42 ` Lionel Bouton
2006-09-30 23:27 ` [gentoo-dev] " Ryan Hill
2006-09-30 21:48 ` Ryan Hill
2006-09-30 21:52 ` Robin H. Johnson
2006-09-30 22:37 ` Ryan Hill
2006-10-01 0:38 ` Robin H. Johnson
2006-10-01 11:23 ` Duncan
2006-10-01 16:49 ` Donnie Berkholz
2006-10-01 17:02 ` Diego 'Flameeyes' Pettenò
2006-10-01 18:00 ` Ryan Hill
2006-10-02 10:40 ` Duncan
2006-10-01 21:01 ` Jeroen Roovers
2006-10-01 0:37 ` [gentoo-dev] " George Prowse
-- strict thread matches above, loose matches on Subject: below --
2006-10-03 0:56 Lionel Bouton
2006-10-03 11:55 ` Chris Gianelloni
2006-10-03 12:26 ` Ciaran McCreesh
2006-10-03 13:15 ` Mike Frysinger
2006-10-04 8:35 ` Jan Kundrát
2006-10-03 22:37 ` Lionel Bouton
2006-10-04 12:25 ` Paul de Vrieze
2006-10-03 16:11 ` Josh Saddler
2006-10-03 17:16 ` Lionel Bouton
2006-10-03 17:22 ` Daniel Ostrow
2006-10-03 17:47 ` Charlie
2006-10-03 17:56 ` Stephen P. Becker
2006-10-03 17:49 ` Lionel Bouton
2006-10-03 20:46 ` Chris Gianelloni
2006-10-03 22:14 ` Lionel Bouton
2006-10-03 18:08 ` Simon Stelling
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