[CentOS-devel] CentOS 7 (1503) i686 Beta Architecture

Vladimir Stackov amigo.elite at gmail.com
Sat Jun 6 13:09:12 UTC 2015


Ok, what should I do if I'm ready to maintain packages for public non-sse2
rebuild? How to get this rebuild covered by CentOS SIG?

As far as I know I'm prohibited to use "CentOS" in public rebuild name
until it was explicitly allowed by CentOS project.
06.06.2015 12:44 пользователь "Johnny Hughes" <johnny at centos.org> написал:

> On 06/06/2015 02:43 AM, Toni Spets wrote:
> >
> >
> > On Sat, Jun 6, 2015 at 12:09 AM, Johnny Hughes <johnny at centos.org
> > <mailto:johnny at centos.org>> wrote:
> >
> >     On 06/05/2015 03:41 PM, Trevor Hemsley wrote:
> >     > Is it really worth the effort? The last Pentium III was released
> in 2002
> >     > and you couldn't buy them after 2003 so we're talking about
> machines
> >     > that are 12 or more years old. The fastest one you could ever buy
> is
> >     > outperformed by a factor of more than 2 times by each core on my
> dual
> >     > core 2010 vintage Intel Atom D510.
> >     >
> >
> >     I don't mind the effort of compiling so much as the potential for
> >     massive confusion with 2 packages named the same thing but compiled
> with
> >     different gcc optimizations, as we would still have to provide the
> other
> >     packages i686 packages in x86_64 arch for multilib.
> >
> >
> > Why its there a need to provide two different builds? Couldn't the
> > multilib packages be rebuilt not to require SSE2? Is the performance
> > penalty bad enough to not even consider it?
>
> The reason the items in CentOS 7 x86_64 (in this case, we are taking
> about the i686 multilib pacakges) need to be built with an unmodified
> gcc is that the whole goal of CentOS Linux is to build packages from
> RHEL sources that are as close to possible to actual Red Hat packages
> minus branding.
>
> If we change the way gcc produces those i686 packages that we put into
> our main CentOS 7 x86_64 arch then that is a huge difference.  I am
> quite sure our users do not want us modifying CentOS Linux 7 production
> packages in this manner.
>
> If has nothing to do with performance, it has to do with producing
> CentOS Linux 7 x86_64 that deviates from the way the upstream packages
> are produced.
>
>
> >
> >
> >
> >     But, I do agree that trying to run this on 12 year old machines is is
> >     not going to be easy.  CentOS-7 does not perform well without at
> least
> >     1.5GB - 2GB of RAM as well.  (The installer does not even work well
> with
> >     less than 1 GB RAM)
> >
> >
> > The installer does run with 512MB of RAM and it can be run around 384MB
> > of RAM as well without any modifications except lowering the requirement
> > by hand. The use cases would be headless environments like servers where
> > you can better utilize the memory like you do in virtualized
> > environments. I do have 512MB CentOS 7 64-bit VMs that perform just fine
> > for what they are tasked for.
> >
> >
> >
> >     If enough people really want it, I guess it could be done as part of
> the
> >     AltArch Special Interest Group .. but my initial take is not positive
> >     because of the confusion potential.
> >
> >
> >     > On 05/06/15 21:22, Toni Spets wrote:
> >     >> This would be rather unfortunate as that would also leave out all
> >     >> 32-bit only AMD processors (Athlon XP & co) as well according to
> >     >> Wikipedia where it's said Athlon 64 was the first one to add SSE2
> and
> >     >> it can already run the 64-bit CentOS anyway.
> >     >>
> >     >> I'm hoping there is more people that could +1 having support for
> >     >> pre-SSE2 CPUs so it would be seriously considered even though it
> might
> >     >> need massive rebuild of the multilib packages. EPEL doesn't have
> >     >> multilib yet (right?) so they can still adapt to whatever is
> going to
> >     >> be done. The packages would run on upstream as well anyway.
> >     >>
> >     >> Taking into account the actual computing power of CPUs, I don't
> think
> >     >> it's unreasonable to run CentOS 7 on Pentium III or Athlon XP.
> >     >>
> >     >> Thanks for considering.
> >     >>
> >     >> On Fri, Jun 5, 2015 at 9:44 PM, Johnny Hughes <johnny at centos.org
> <mailto:johnny at centos.org>
> >     >> <mailto:johnny at centos.org <mailto:johnny at centos.org>>> wrote:
> >     >>
> >     >>     On 06/05/2015 05:46 AM, Vladimir Stackov wrote:
> >     >>     > Greetings,
> >     >>     >
> >     >>     > currently we are maintaining own CentOS 7 i686 rebuild and I
> >     >>     would like
> >     >>     > to kindly ask you to replace following macros from gcc.spec:
> >     >>     >
> >     >>     > %if 0%{?rhel} >= 7
> >     >>     > %ifarch %{ix86}
> >     >>     >    --with-arch=x86-64 \
> >     >>     > %endif
> >     >>     > %ifarch x86_64
> >     >>     >    --with-arch_32=x86-64 \
> >     >>     > %endif
> >     >>     >
> >     >>     > with that:
> >     >>     >
> >     >>     > %if 0%{?rhel} >= 7
> >     >>     > %ifarch %{ix86}
> >     >>     >         --with-arch=i686 \
> >     >>     > %endif
> >     >>     > %ifarch x86_64
> >     >>     >         --with-arch_32=i686 \
> >     >>     > %endif
> >     >>     >
> >     >>     > x86-64 causes gcc to use extended instruction set for
> produced
> >     >>     code and
> >     >>     > it's impossible to run CentOS 7 i686 on older systems
> >     without SSE2
> >     >>     > instruction because of SIGILL.
> >     >>     > This affects Pentium 3, old VIA CPUs, old Xeons and some
> >     others.
> >     >>     >
> >     >>     > Is that possible?
> >     >>     > Thanks!
> >     >>     >
> >     >>
> >     >>     <snip>
> >     >>
> >     >>     I don't think we can do this as I also use the RPMs produced
> >     for the
> >     >>     multilib portion of CentOS-7 x86_64 and we want our RPMs to
> >     be like
> >     >>     those from upstream for that purpose.
> >     >>
> >     >>     Thanks,
> >     >>     Johnny Hughes
> >     >>
> >     >>
> >
> >
> >
> >     _______________________________________________
> >     CentOS-devel mailing list
> >     CentOS-devel at centos.org <mailto:CentOS-devel at centos.org>
> >     http://lists.centos.org/mailman/listinfo/centos-devel
> >
> >
> >
> >
> > --
> > Toni Spets
> >
> >
> > _______________________________________________
> > CentOS-devel mailing list
> > CentOS-devel at centos.org
> > http://lists.centos.org/mailman/listinfo/centos-devel
> >
>
>
>
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