[gentoo-user] USE="custom-optimization"

[gentoo-user] USE="custom-optimization"

[Florian Philipp]

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Hi list!

I'm wondering how to interpret the custom-optimization use flag which
has become much more common in the recent weeks/months.

I mean, I understand the basic concept: it either uses the cflags from
my make.conf or its own set. But what exactly does the dev want to tell
me when she uses this flag and sets it to default off?

1. "If you have a fancy set of uncommon cflags, this package might break
in funny ways. Therefore you might want to use my set of conservative
flags instead."

2. "In order to run perfectly, this package needs a very unique set of
cflags. Trust me to set them properly if you have a rather common system."

3. "No one will give you support when this package breaks unless you use
the default compile flags. However, for optimal performance you might
still want to use your own set of flags."

I'm asking because very different packages have started using this flag,
for example Firefox and ffmpeg. For Firefox, I'd think the dev thought
of 1 or 3. With ffmpeg, number 2 might be the right interpretation,
especially as it seems to set such uncommon flags as -O3 (which always
decreased performance when I tried it for other packages or my own
programs).

Just for the records: I'm using a conservative set of cflags:
-march=core2 and -O2


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Re: [gentoo-user] USE="custom-optimization"

[Albert Hopkins]

On Thu, 2009-05-21 at 12:30 +0200, Florian Philipp wrote:
> Hi list!
> 
> I'm wondering how to interpret the custom-optimization use flag which
> has become much more common in the recent weeks/months.
> 
> I mean, I understand the basic concept: it either uses the cflags from
> my make.conf or its own set. But what exactly does the dev want to tell
> me when she uses this flag and sets it to default off?

[...]

I'm not sure how you mean "much more common" as of the over 700 packages
I have installed only 1 offers that flag, but...

The package is sensitive to CFLAGS.  There is a set of flags that the
devs will support.  For convenience, they have given you the option of
choosing your own, but if you do then you're on your own :)

-a

Re: [gentoo-user] USE="custom-optimization"

[Florian Philipp]

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Albert Hopkins schrieb:
> On Thu, 2009-05-21 at 12:30 +0200, Florian Philipp wrote:
>> Hi list!
>>
>> I'm wondering how to interpret the custom-optimization use flag which
>> has become much more common in the recent weeks/months.
>>
>> I mean, I understand the basic concept: it either uses the cflags from
>> my make.conf or its own set. But what exactly does the dev want to tell
>> me when she uses this flag and sets it to default off?
> 
> [...]
> 
> I'm not sure how you mean "much more common" as of the over 700 packages
> I have installed only 1 offers that flag, but...
> 

Well, "much more common" might be an exaggeration and I've also mixed
custom-optimization (firefox and xulrunner) with custom-cflags (grub,
ffmpeg and libsdl).


> The package is sensitive to CFLAGS.  There is a set of flags that the
> devs will support.  For convenience, they have given you the option of
> choosing your own, but if you do then you're on your own :)
> 

So it's really just a support-thing, nothing like "we know better"?
Thanks. In this case, I will use my own flags again.


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