Re: armelfp: new architecture name for an armel variant
On Thu, Jul 15, 2010 at 08:06:42PM +0300, Konstantinos Margaritis wrote:
> On Thursday 15 July 2010 19:48:43 Aurelien Jarno wrote:
> > Note that the new alternative to hwcap is called "multiarch" in the GNU
> > libc (something totally different than "multiarch" in Debian). It allows
> > to provide different versions of a given symbol using an IFUNC symbol
> > type. This will be resolved by the dynamic loader during relocation
> > depending on the hardware characteristics.
> >
> > This avoid building multiple version of the same software (but still
> > multiple versions of a given function), and to introduce more
> > granularity (e.g. on x86 SSE, SSE2, SSE3, SSSE4.2, AVX, etc).
>
> So, in essence an application/library can include in the same binary multiple
> versions of the same function and the system picks one depending on the
> current cpu capabilities? So things like autodetecting SSE/Altivec, etc are
> not needed anymore?
For libraries sure. I think it might be possible to also get it working
for binaries, though I haven't looked more in details.
Note that you need a recent toolchain for that (binutils and glibc).
> > Currently only x86, x86_64, ia64, powerpc and sparc are supported, but
> > it should not be difficult to add support for more architectures.
>
> I'm interested in that, is it documented somewhere? ( I know the old hwcap was
> not at all, unless one wanted to read half of glibc source code).
>
I am afraid there are not a lot of documentation, beside the glibc
source code. This patch can be interesting though:
http://old.nabble.com/indirect-function-support-td28576476.html
--
Aurelien Jarno GPG: 1024D/F1BCDB73
aurelien@aurel32.net http://www.aurel32.net
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