[openfabrics-ewg] 32-bit build for ppc64 is required

[Doug Ledford]

On Thu, 2007-02-15 at 18:29 +0200, Michael S. Tsirkin wrote:
> > Quoting Doug Ledford <dledford at redhat.com>:
> > Subject: Re: 32-bit build for ppc64 is required
> > 
> > On Thu, 2007-02-15 at 07:57 +0200, Michael S. Tsirkin wrote:
> > 
> > > > The choice of 32/64 bit default is done on a per arch basis.  With
> > > > x86_64/i386, the increased number of CPU registers in 64bit mode
> > > > outweighs the increased code bloat that goes along with 64bit mode.  On
> > > > PPC, no such register benefit exists for 64bit mode.  As such, 32bit
> > > > apps on PPC are faster than the equivalent 64bit apps up to the point at
> > > > which a 4GB address space becomes a problem.  Correspondingly, the
> > > > default binaries on PPC are 32bit, and only those that *need* to be
> > > > 64bit are.  While a customer's application may need >4GB address space,
> > > > certainly all the ibutils, diags, opensm, etc. do not.  As a result, we
> > > > compile all of those utilities as 32bit by default on PPC.  We also ship
> > > > all the libs as both 32/64bit so users can select the appropriate
> > > > environment for their particular application (with the exception of
> > > > dapl, which doesn't support 32bit and for which I filed a bug around the
> > > > time of OFED 1.1).
> > > 
> > > So, what you suggest is - build 2 types of libraries, but on PPC make
> > > binaries 32 bit? That's easy - do others agree to this approach?
> > 
> > Yep, that's what we do.
> 
> Care to post a patch to Vlad's scripts?

Yuk.  I suppose I could write one, but I don't (and can't) use any of
the OFED supplied build scripts in our build system, so it's hard for me
to test since our build system is the only way I have to access
ppc/ppc64 hardware.

-- 
Doug Ledford <dledford at redhat.com>
              GPG KeyID: CFBFF194
              http://people.redhat.com/dledford

Infiniband specific RPMs available at
              http://people.redhat.com/dledford/Infiniband
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