Re: future of the libc6.1-alphaev67 package
Hi,
On 2021-09-02 23:29, Aurelien Jarno wrote:
> Hi,
>
> On 2021-08-25 13:47, Michael Cree wrote:
> > On Tue, Aug 24, 2021 at 10:59:32PM +0200, Aurelien Jarno wrote:
> > > I would therefore like to discuss the future of the libc6.1-alphaev67
> > > package on alpha. According to popcon, to take with a grain of salt
> > > given the low number of submissions, this package is installed on 20% of
> > > the installations. I wonder if this package is really useful in terms of
> > > performance, or if the architecture baseline can be raised to ev67, or
> > > to a ev6 as a compromise. The goal is to stop building this package.
> >
> > I think we should raise the baseline to include the byte-word
> > extension (BWX) which I think would be EV56. In addition to
> > giving some optimisations generally to libc it would eliminate
> > a class of unaligned access bugs across the archive where gcc
> > performs an optimisation based on a flawed determination that
> > certain alignment exists in the memory access of a byte or
> > 16-bit word.
>
> That's really interesting. If raising the baseline to EV56 also helps to
> eliminate other bugs, it's something worth considering. Do you know if
> there is a lot of hardware not compatible with this baseline? Also do
> you have an idea if there is a big difference between EV56 and EV67
> optimized code?
The legacy hwcap code, that was deprecated since glibc 2.33 has been
removed from glibc 2.37, and there is no support for the new mechanism
for the alpha architecture.
Therefore the libc6.1-alphaev67 package will be removed from the debian
package with glibc 2.37. We can take the opportunity to raise the
baseline if needed.
Regards
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://aurel32.net
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