Re: future of the libc6.1-alphaev67 package

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?

Regards,
Aurelien