[gentoo-user] Advice for 64-bit n00b?

[gentoo-user] Advice for 64-bit n00b?

[Stroller]

Hi there,

A new (to me) server has 64-bit CPUs. By my standards this is a REALLY  
NICE high specification machine (I appears to be 2 x dual-core), but  
in fact it's about 3 years old & is one of the earliest Intel Xeons  
that supports 64-bits / AMD64 / EMT64. I think it is 64-bit Pentium 4,  
rather than Core 2 architecture.

# cat /proc/cpuinfo | head -n 25
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      : Intel(R) Xeon(TM) CPU 3.00GHz
stepping        : 3
cpu MHz         : 2992.346
cache size      : 2048 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 1
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge  
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe  
syscall nx lm constant_tsc pebs bts pni dtes64 monitor ds_cpl cid cx16  
xtpr
bogomips        : 5984.69
clflush size    : 64
cache_alignment : 128
address sizes   : 36 bits physical, 48 bits virtual
power management:


I'm a bit confused by the 36-bit address size mentioned there, but I  
assume this is OK. The Gentoo wiki seems to confirm this CPU is 64- 
bit: http://tinyurl.com/klv7gc [1]

Is there anything I need to know about working with 64-bits / AMD64 /  
EMT64, seeing as I've never done so before?

I have started following the Gentoo Linux AMD64 Handbook, because the  
Quick Install Guide is described as "x86". Having untarred the stage I  
am surprised to find a lib32 directory. I thought compatibility with  
32-bit binaries was optional. Or am I misunderstanding? This is going  
to be a headless server & I can't think that it'll need any binary  
packages - possibly the management utility for the RAID controller  
will be distributed as a binary, I'm not sure yet (the hardware RAID  
key was missing when I got this machine ☹)

I'm editing my make.conf and looked at the Gentoo wiki for "Safe  
Cflags" - it says 'CHOST="x86_64-pc-linux-gnu"'. But of course  
(according to make.conf.example) one shouldn't change CHOST on an  
installed system. Will the files in the stage 3 have been compiled  
using this CHOST?

Any pointers would be gratefully appreciated - I'm wondering if  
there's anything you guys all take for granted that I could mess up if  
I don't allow for it early enough in the installation process.

Thanks in advance for any comments,

Stroller.




[1] http://en.gentoo-wiki.com/wiki/Safe_Cflags/Intel#Xeon_w.2FEM64T_.28also_Pentium_4_P6xx_or_Celeron_M_5xx.29 
  

Re: [gentoo-user] Advice for 64-bit n00b?

[Alan McKinnon]

On Wednesday 03 March 2010 17:29:06 Stroller wrote:
> Hi there,
> 
> A new (to me) server has 64-bit CPUs. By my standards this is a REALLY
> NICE high specification machine (I appears to be 2 x dual-core), but
> in fact it's about 3 years old & is one of the earliest Intel Xeons
> that supports 64-bits / AMD64 / EMT64. I think it is 64-bit Pentium 4,
> rather than Core 2 architecture.
> 
> # cat /proc/cpuinfo | head -n 25
> processor       : 0
> vendor_id       : GenuineIntel
> cpu family      : 15
> model           : 4
> model name      : Intel(R) Xeon(TM) CPU 3.00GHz
> stepping        : 3
> cpu MHz         : 2992.346
> cache size      : 2048 KB
> physical id     : 0
> siblings        : 2
> core id         : 0
> cpu cores       : 1
> apicid          : 0
> initial apicid  : 0
> fpu             : yes
> fpu_exception   : yes
> cpuid level     : 5
> wp              : yes
> flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
> mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
> syscall nx lm constant_tsc pebs bts pni dtes64 monitor ds_cpl cid cx16
> xtpr
> bogomips        : 5984.69
> clflush size    : 64
> cache_alignment : 128
> address sizes   : 36 bits physical, 48 bits virtual
> power management:
> 
> 
> I'm a bit confused by the 36-bit address size mentioned there, but I
> assume this is OK. The Gentoo wiki seems to confirm this CPU is 64-
> bit: http://tinyurl.com/klv7gc [1]

that is correct


> 
> Is there anything I need to know about working with 64-bits / AMD64 /
> EMT64, seeing as I've never done so before?

Nope, it's just another arch. The days of doing weird funky stuff to get amd64 
to work are long gone


> 
> I have started following the Gentoo Linux AMD64 Handbook, because the
> Quick Install Guide is described as "x86". Having untarred the stage I
> am surprised to find a lib32 directory. I thought compatibility with
> 32-bit binaries was optional. Or am I misunderstanding? This is going
> to be a headless server & I can't think that it'll need any binary
> packages - possibly the management utility for the RAID controller
> will be distributed as a binary, I'm not sure yet (the hardware RAID
> key was missing when I got this machine ☹)
> 
> I'm editing my make.conf and looked at the Gentoo wiki for "Safe
> Cflags" - it says 'CHOST="x86_64-pc-linux-gnu"'. But of course
> (according to make.conf.example) one shouldn't change CHOST on an
> installed system. Will the files in the stage 3 have been compiled
> using this CHOST?

Yes. If you used a recent amd64 stage, it will all be fine.
> 
> Any pointers would be gratefully appreciated - I'm wondering if
> there's anything you guys all take for granted that I could mess up if
> I don't allow for it early enough in the installation process.

In make,conf, as long s you are using a reasonably recent gcc:

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=native -O2 -pipe"
CXXFLAGS="${CFLAGS}"


-march=native avoids all that tedious mucking about with trying to figure out 
what cpu type you should build for, and moves the heavy lifting off onto the 
compiler.



-- 
alan dot mckinnon at gmail dot com

Re: [gentoo-user] Advice for 64-bit n00b?

[Stroller]

On 3 Mar 2010, at 15:29, Stroller wrote:
> ...
> I have started following the Gentoo Linux AMD64 Handbook, because  
> the Quick Install Guide is described as "x86". Having untarred the  
> stage I am surprised to find a lib32 directory. I thought  
> compatibility with 32-bit binaries was optional. Or am I  
> misunderstanding? This is going to be a headless server & I can't  
> think that it'll need any binary packages - possibly the management  
> utility for the RAID controller will be distributed as a binary, I'm  
> not sure yet (the hardware RAID key was missing when I got this  
> machine ☹)


Further to Alan's reply, I've proceeded a little further.

I'm onto section 2.3: Changing profiles, where it says:
   "If you want to have a pure 64-bit environment, with no 32-bit  
applications or libraries, you should use a non-multilib profile."

See my comments in the quoted above. It shouldn't be too expensive to  
enable the RAID in this machine (which is on the mainboard, but  
requires a little hardware PCB "key" to be fitted). That's a Dell  
PERC4, which AFAICT is a rebadged LSI megaraid.

This post [1] http://tinyurl.com/3dzcl9 referrs to the management  
utility thus: "MegaCLI comes as a RPM containing only a single  
statically linked 32-bit Linux binary", however `eix mega` suggests  
there may be alternatives, such as `megactl` [2]

My immediate thought when reading the handbook was that it's "best"  
and "cleanest" and "more right" to only have 64-bit libraries on a 64- 
bit system, but this need for the RAID management utility is making me  
wonder if that would be cutting off my nose to spite my face.

Thoughts?

Stroller.




[1] http://www.kaltenbrunner.cc/blog/index.php?/archives/4-LSIlogic-MegaRAID-SAS-and-the-self-explaining-CLI.html

[2] http://sourceforge.net/projects/megactl/

Re: [gentoo-user] Advice for 64-bit n00b?

[Alan McKinnon]

On Wednesday 03 March 2010 19:04:45 Stroller wrote:
> On 3 Mar 2010, at 15:29, Stroller wrote:
> > ...
> > I have started following the Gentoo Linux AMD64 Handbook, because
> > the Quick Install Guide is described as "x86". Having untarred the
> > stage I am surprised to find a lib32 directory. I thought
> > compatibility with 32-bit binaries was optional. Or am I
> > misunderstanding? This is going to be a headless server & I can't
> > think that it'll need any binary packages - possibly the management
> > utility for the RAID controller will be distributed as a binary, I'm
> > not sure yet (the hardware RAID key was missing when I got this
> > machine ☹)
> 
> Further to Alan's reply, I've proceeded a little further.
> 
> I'm onto section 2.3: Changing profiles, where it says:
>    "If you want to have a pure 64-bit environment, with no 32-bit
> applications or libraries, you should use a non-multilib profile."
> 
> See my comments in the quoted above. It shouldn't be too expensive to
> enable the RAID in this machine (which is on the mainboard, but
> requires a little hardware PCB "key" to be fitted). That's a Dell
> PERC4, which AFAICT is a rebadged LSI megaraid.
> 
> This post [1] http://tinyurl.com/3dzcl9 referrs to the management
> utility thus: "MegaCLI comes as a RPM containing only a single
> statically linked 32-bit Linux binary", however `eix mega` suggests
> there may be alternatives, such as `megactl` [2]
> 
> My immediate thought when reading the handbook was that it's "best"
> and "cleanest" and "more right" to only have 64-bit libraries on a 64-
> bit system, but this need for the RAID management utility is making me
> wonder if that would be cutting off my nose to spite my face.

It has a single statically linked binary. Which probably means it already 
contains everything you will need and will run just fine. No need to build 
everything multilib; if you do need a 32bit lib, just install the appropriate 
emul-x86-linux package.

-- 
alan dot mckinnon at gmail dot com

Re: [gentoo-user] Advice for 64-bit n00b?

[Mick]

[-- Attachment #1: Type: Text/Plain, Size: 2345 bytes --]

On Wednesday 03 March 2010 20:04:17 Alan McKinnon wrote:
> On Wednesday 03 March 2010 19:04:45 Stroller wrote:
> > On 3 Mar 2010, at 15:29, Stroller wrote:
> > > ...
> > > I have started following the Gentoo Linux AMD64 Handbook, because
> > > the Quick Install Guide is described as "x86". Having untarred the
> > > stage I am surprised to find a lib32 directory. I thought
> > > compatibility with 32-bit binaries was optional. Or am I
> > > misunderstanding? This is going to be a headless server & I can't
> > > think that it'll need any binary packages - possibly the management
> > > utility for the RAID controller will be distributed as a binary, I'm
> > > not sure yet (the hardware RAID key was missing when I got this
> > > machine ☹)
> >
> > Further to Alan's reply, I've proceeded a little further.
> >
> > I'm onto section 2.3: Changing profiles, where it says:
> >    "If you want to have a pure 64-bit environment, with no 32-bit
> > applications or libraries, you should use a non-multilib profile."
> >
> > See my comments in the quoted above. It shouldn't be too expensive to
> > enable the RAID in this machine (which is on the mainboard, but
> > requires a little hardware PCB "key" to be fitted). That's a Dell
> > PERC4, which AFAICT is a rebadged LSI megaraid.
> >
> > This post [1] http://tinyurl.com/3dzcl9 referrs to the management
> > utility thus: "MegaCLI comes as a RPM containing only a single
> > statically linked 32-bit Linux binary", however `eix mega` suggests
> > there may be alternatives, such as `megactl` [2]
> >
> > My immediate thought when reading the handbook was that it's "best"
> > and "cleanest" and "more right" to only have 64-bit libraries on a 64-
> > bit system, but this need for the RAID management utility is making me
> > wonder if that would be cutting off my nose to spite my face.
> 
> It has a single statically linked binary. Which probably means it already
> contains everything you will need and will run just fine. No need to build
> everything multilib; if you do need a 32bit lib, just install the
>  appropriate emul-x86-linux package.

So how 'safe' is it these days to build a 64bit only system?  Would you end up 
having to rebuild with multilibs because many apps which won't work on a pure 
64bit build?
-- 
Regards,
Mick

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 198 bytes --]

Re: [gentoo-user] Advice for 64-bit n00b?

[Volker Armin Hemmann]

On Mittwoch 03 März 2010, Mick wrote:

> So how 'safe' is it these days to build a 64bit only system?  Would you end
> up having to rebuild with multilibs because many apps which won't work on
> a pure 64bit build?


no, it is not safe to have a 64bit only system. Just choose the multilib 
profile and start installing. If something needs the 32bit emul libs, it will 
pull the stuff in. There is nothing you need to care about.

Re: [gentoo-user] Advice for 64-bit n00b?

[Graham Murray]

Volker Armin Hemmann <volkerarmin@googlemail.com> writes:

> no, it is not safe to have a 64bit only system. Just choose the multilib 
> profile and start installing. If something needs the 32bit emul libs, it will 
> pull the stuff in. There is nothing you need to care about.

What is unsafe about a 64bit only system? Surely if it were unsafe then
Gentoo would not offer no-multilib profiles? I have recently built 2
systems using a no-multilib profile and have not found any problems, and
expect to start building a third one today.

[gentoo-user] Re: Advice for 64-bit n00b?

[Nikos Chantziaras]

On 03/04/2010 08:44 AM, Graham Murray wrote:
> Volker Armin Hemmann<volkerarmin@googlemail.com>  writes:
>
>> no, it is not safe to have a 64bit only system. Just choose the multilib
>> profile and start installing. If something needs the 32bit emul libs, it will
>> pull the stuff in. There is nothing you need to care about.
>
> What is unsafe about a 64bit only system? Surely if it were unsafe then
> Gentoo would not offer no-multilib profiles? I have recently built 2
> systems using a no-multilib profile and have not found any problems, and
> expect to start building a third one today.

You didn't understand the question Volker was replying to.  The question 
was not about "safe" as in "security", but rather "safe" as in "I can 
rest assured that a no-multilib system can run every software I could 
install", which is clearly not the case since some applications need 
32-bit support.

Re: [gentoo-user] Advice for 64-bit n00b?

[Zeerak Mustafa Waseem]

[-- Attachment #1: Type: text/plain, Size: 1250 bytes --]

On Thu, Mar 04, 2010 at 06:44:27AM +0000, Graham Murray wrote:
> Volker Armin Hemmann <volkerarmin@googlemail.com> writes:
> 
> > no, it is not safe to have a 64bit only system. Just choose the multilib 
> > profile and start installing. If something needs the 32bit emul libs, it will 
> > pull the stuff in. There is nothing you need to care about.
> 
> What is unsafe about a 64bit only system? Surely if it were unsafe then
> Gentoo would not offer no-multilib profiles? I have recently built 2
> systems using a no-multilib profile and have not found any problems, and
> expect to start building a third one today.
> 

I completely misread that, I read it as "it is safe to have a 64bit only system".

I ran a no-multilib profile for a couple of weeks which ran fine. This isn't a long period of time, I know. But I had absolutely no issues in that period. The only reason I switched back to a multilib profile was because a math program for school couldn't connect to it's core functions on a pure 64-bit environment. 
Furthermore, I have multilib flag disabled as standard, but there are some things (gcc, glibc mainly) where I have set the multilib flag. And I'm not having any sort of problem with it.

-- 
Zeerak Waseem

[-- Attachment #2: Type: application/pgp-signature, Size: 490 bytes --]

Re: [gentoo-user] Advice for 64-bit n00b?

[Alan McKinnon]

On Thursday 04 March 2010 08:44:27 Graham Murray wrote:
> Volker Armin Hemmann <volkerarmin@googlemail.com> writes:
> > no, it is not safe to have a 64bit only system. Just choose the multilib
> > profile and start installing. If something needs the 32bit emul libs, it
> > will pull the stuff in. There is nothing you need to care about.
> 
> What is unsafe about a 64bit only system? Surely if it were unsafe then
> Gentoo would not offer no-multilib profiles? I have recently built 2
> systems using a no-multilib profile and have not found any problems, and
> expect to start building a third one today.


It's not unsafe in that the machine cannot work, it's unsafe in that for a 
normal desktop user's range of apps, some thing might be impossible to get 
going.

If you have a no-multilib desktop profile, and you need to install some thrid 
party app like VPN software that is 32 bit, you are stuck needing a reinstall 
(as that profile switch on a live machine is not easy nor advised).

Just be safe as use the profile that will let you use 32 bit libs if and when 
you need them.


-- 
alan dot mckinnon at gmail dot com

Re: [gentoo-user] Re: Advice for 64-bit n00b?

[Volker Armin Hemmann]

On Donnerstag 04 März 2010, Nikos Chantziaras wrote:
> On 03/04/2010 08:44 AM, Graham Murray wrote:
> > Volker Armin Hemmann<volkerarmin@googlemail.com>  writes:
> >> no, it is not safe to have a 64bit only system. Just choose the multilib
> >> profile and start installing. If something needs the 32bit emul libs, it
> >> will pull the stuff in. There is nothing you need to care about.
> > 
> > What is unsafe about a 64bit only system? Surely if it were unsafe then
> > Gentoo would not offer no-multilib profiles? I have recently built 2
> > systems using a no-multilib profile and have not found any problems, and
> > expect to start building a third one today.
> 
> You didn't understand the question Volker was replying to.  The question
> was not about "safe" as in "security", but rather "safe" as in "I can
> rest assured that a no-multilib system can run every software I could
> install", which is clearly not the case since some applications need
> 32-bit support.

exactly. As Alan explained, there might be a point where you need to run a 
32bit app.
Maybe some legacy game (Civilization Call To Power comes to mind) or some new-
but-the-vendor-sucks software.
Without multilib you can either choose not to use that software (which isn't a 
choice if you really need it) or you can reinstall everything.

And all that for a couple of megabytes on a tens, maybe hundreds of gigabytes 
harddisk.

du -h /usr/lib32
362M    /usr/lib32

but:
rootfs                 57G   23G   34G  41% /

yeah, shocking. Almost a 114th of the harddisk used for multilib stuff ;)

Re: [gentoo-user] Re: Advice for 64-bit n00b?

[Stroller]

On 4 Mar 2010, at 07:19, Nikos Chantziaras wrote:

> On 03/04/2010 08:44 AM, Graham Murray wrote:
>> Volker Armin Hemmann<volkerarmin@googlemail.com>  writes:
>>
>>> no, it is not safe to have a 64bit only system. Just choose the  
>>> multilib
>>> profile and start installing. If something needs the 32bit emul  
>>> libs, it will
>>> pull the stuff in. There is nothing you need to care about.
>>
>> What is unsafe about a 64bit only system? Surely if it were unsafe  
>> then
>> Gentoo would not offer no-multilib profiles? I have recently built 2
>> systems using a no-multilib profile and have not found any  
>> problems, and
>> expect to start building a third one today.
>
> You didn't understand the question Volker was replying to.  The  
> question was not about "safe" as in "security", but rather "safe" as  
> in "I can rest assured that a no-multilib system can run every  
> software I could install", which is clearly not the case since some  
> applications need 32-bit support.

I could imagine that web-browsers might need 32-bit support in order  
to play Flash, but can you suggest other applications which might?

This is a headless server, and I was kinda reassured by Alan's  
response (Wed, 3 Mar 2010 22:04:17 +0200) [1] that seemed to assure me  
that a statically linked 32-bit binary would work fine if I selected  
the "no-multilib" profile.

I'd be really quite happy if I knew that this decision was revocable -  
if I could choose "no-multilib" now and change my mind using eselect  
later. Presumably  I can choose to keep these 32-bit libs for the  
moment & blow them away if I find I don't need them - this lib32 is,  
after all, in the stage3-amd64-*tar.bz2, so what is the point in  
offering me "no-multilib" if I can't do that?

Stroller.



[1] http://archives.gentoo.org/gentoo-user/msg_64a30b77742cf5846705952e6129367d.xml
http://tinyurl.com/ykvx5co

Re: [gentoo-user] Re: Advice for 64-bit n00b?

[Volker Armin Hemmann]

On Donnerstag 04 März 2010, Stroller wrote:

> 
> I'd be really quite happy if I knew that this decision was revocable -
> if I could choose "no-multilib" now and change my mind using eselect
> later. Presumably  I can choose to keep these 32-bit libs for the
> moment & blow them away if I find I don't need them - this lib32 is,
> after all, in the stage3-amd64-*tar.bz2, so what is the point in
> offering me "no-multilib" if I can't do that?

you can not change on the fly. going from no-multilib to multilib means re-
installation.
no-multilib is meant for the very brave or people who know exactly that they 
never need 32bit apps on that box.

Your manpages will take up more space then those few 32bit emul libs that 
might or not be installed. So there is no downside going multilib.

Re: [gentoo-user] Re: Advice for 64-bit n00b?

[Mick]

On 4 March 2010 09:15, Volker Armin Hemmann <volkerarmin@googlemail.com> wrote:
> On Donnerstag 04 März 2010, Stroller wrote:
>
>>
>> I'd be really quite happy if I knew that this decision was revocable -
>> if I could choose "no-multilib" now and change my mind using eselect
>> later. Presumably  I can choose to keep these 32-bit libs for the
>> moment & blow them away if I find I don't need them - this lib32 is,
>> after all, in the stage3-amd64-*tar.bz2, so what is the point in
>> offering me "no-multilib" if I can't do that?
>
> you can not change on the fly. going from no-multilib to multilib means re-
> installation.
> no-multilib is meant for the very brave or people who know exactly that they
> never need 32bit apps on that box.
>
> Your manpages will take up more space then those few 32bit emul libs that
> might or not be installed. So there is no downside going multilib.

Yep, that was my decision too for a desktop installation.  If I were
building a slim server and checked that all apps required are
available as 64bit I might have chosen a no-multilib profile.  For
anything else I probably wouldn't.
-- 
Regards,
Mick

Re: [gentoo-user] Re: Advice for 64-bit n00b?

[Walter Dnes]

On Thu, Mar 04, 2010 at 08:56:34AM +0000, Stroller wrote

> I could imagine that web-browsers might need 32-bit support in order  
> to play Flash

  If you're brave, there's an alpha (as in pre-beta, not the CPU) 64-bit
plugin for linux at...
http://labs.adobe.com/downloads/flashplayer10_64bit.html

> but can you suggest other applications which might?

  Realplayer, or any other proprietary plugin.

-- 
Walter Dnes <waltdnes@waltdnes.org>