Re: Problem with VIA C3 chip and libcrypto
At Mon, 4 Nov 2002 11:07:56 +0100,
Oliver M. Bolzer <firstname.lastname@example.org> wrote:
> On Mon, Nov 04, 2002 at 09:23:16AM +0000, Ricardo Javier Cardenes Medina <email@example.com> wrote...
> > On Sun, Nov 03, 2002 at 12:13:07PM +0100, Michael Karcher wrote:
> > > take profit of these instructions, but It seems likely. Is there any way to
> > > select libraries based on 'instruction set' instead of architecture, so
> > > the VIA C3 could get code 'without cmov', the PII 'with cmov and MMX',
> > > the PIII 'with cmov, MMX and SSE' and an Athlon processor 'with cmov, MMX
> > > and 3D now!', although they all are 'family: 6'.
> > See at the end of /proc/cpuinfo. The "flags" field. For my Duron:
> > flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov
> > pat pse36 mmx fxsr syscall mmxext 3dnowext 3dnow
> The problem with OpenSSL is, that it is hand-assembly. The author is using
> the cmov instruction for an i686-optimized routine, though that instruction
> is not guranteed to be available.
I could not find which source cmov is used, could you tell me?
If it's the fact, openssl should be fixed in #164766.
> As another C3 user who has to keep libssl on hold for now, I'd suggest that
> the i686-optimized version be replaced with a version that runs on all
> i686-family processors.
> Another option would be to do runtime detection and choose according to
> that, but that would be without the current convenience that the linker
> chooses the right lib. As long as the linker only decids on the general
> processor type, the code for a specific processor type should match the
> least common denominator.
Yes. It's insane option that linker selects i586 library in only the
case of "flags: cmov" is detected on VIA C3. It means that linker
consider "C3 is i586". So, if kernel detects VIA C3, then it's natural
to be treated with i586 straightforwardly (thus /proc/cpuinfo prints
processor family: i586).