[openfabrics-ewg] 32-bit build for ppc64 is required
Michael S. Tsirkin
mst at mellanox.co.il
Thu Feb 15 09:43:09 PST 2007
> Quoting Doug Ledford <dledford at redhat.com>:
> Subject: Re: 32-bit build for ppc64 is required
> 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.
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