From: "H.J. Lu" <hjl.tools@gmail.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: GNU C Library <libc-alpha@sourceware.org>,
GCC Development <gcc@gcc.gnu.org>,
llvm-dev@lists.llvm.org,
x86-64-abi <x86-64-abi@googlegroups.com>,
"Mallappa, Premachandra" <Premachandra.Mallappa@amd.com>,
Michael Matz <matz@suse.de>, Tom Stellard <tstellar@redhat.com>,
Jeff Law <law@redhat.com>
Subject: Re: New x86-64 micro-architecture levels
Date: Mon, 13 Jul 2020 06:30:07 -0700 [thread overview]
Message-ID: <CAMe9rOphx_GcRh2vWp7mbNv8XiW1v+vaDF3RbN9hpDTYL2YYbQ@mail.gmail.com> (raw)
In-Reply-To: <87y2nnucxm.fsf@oldenburg2.str.redhat.com>
On Sun, Jul 12, 2020 at 11:49 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> > Looks good. I like it.
>
> Thanks. What do you think about Level B? Should we keep it?
Please drop Level B.
> > My only concerns are
> >
> > 1. Names like “x86-100”, “x86-101”, what features do they support?
>
> I think we can add more diagnostic output to ld.so --help. My patch
> does not show individual CPU flags, but I agree this could be useful.
> (It's not needed for the legacy HWCAP subdirectories because in general,
> those are named & defined by the kernel, not by individually named CPU
> feature flags.)
>
> > 2. I have a library with AVX2 and FMA, which directory should it go?
> >
> > Can we pass such info to ld.so and ld.so prints out the best directory
> > name?
>
> I think this would require generating matching GNU property notes (list
> the CPU features required by the binary). Once we have that, we can add
I have turned on -mx86-used-note=yes by default for binutils 2.36.
I will add more ISAs bits after we determine which ISAs will be used.
But compilers need to generate GNU_PROPERTY_X86_ISA_1_NEEDED
property.
> something to binutils or indeed ld.so to analyze them and print the
> recommended directory. But I think this is something that could come
> later.
>
> We can also write a GCC header which looks at macros such as __AVX2__
> and prints a #warning with the recommended directory name. Checking for
> excess flags will be tricky in this context, though, and if we miss
> something, a wrong recommendation will be the result.
>
> Thanks,
> Florian
--
H.J.
next prev parent reply other threads:[~2020-07-13 13:30 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 17:30 Florian Weimer
2020-07-10 19:14 ` Joseph Myers
2020-07-13 7:55 ` Florian Weimer
2020-07-10 21:42 ` H.J. Lu
2020-07-13 6:23 ` Richard Biener
2020-07-13 7:40 ` Florian Weimer
2020-07-13 7:47 ` Jan Beulich
2020-07-13 13:31 ` H.J. Lu
2020-07-13 13:53 ` Jakub Jelinek
2020-07-13 8:57 ` Richard Biener
2020-07-13 6:49 ` Florian Weimer
2020-07-13 13:30 ` H.J. Lu [this message]
2020-07-11 7:40 ` Allan Sandfeld Jensen
2020-07-13 6:58 ` Florian Weimer
2020-07-15 14:38 ` Mark Wielaard
2020-07-15 14:45 ` H.J. Lu
2020-07-15 14:56 ` Florian Weimer
2020-07-21 16:05 ` Mallappa, Premachandra
2020-07-21 18:04 ` Florian Weimer
2020-07-22 1:31 ` Dongsheng Song
2020-07-22 8:44 ` Florian Weimer
2020-07-22 9:26 ` Richard Biener
2020-07-22 10:16 ` Florian Weimer
2020-07-22 13:50 ` Richard Biener
2020-07-22 14:21 ` H.J. Lu
2020-07-31 13:06 ` Carlos O'Donell
2020-07-22 7:48 ` Jan Beulich
2020-07-22 10:34 ` Florian Weimer
2020-07-22 11:41 ` Jan Beulich
2020-07-31 13:20 ` Carlos O'Donell
2020-07-22 16:45 ` Mallappa, Premachandra
2020-07-23 12:44 ` Michael Matz
2020-07-23 13:21 ` H.J. Lu
2020-07-28 15:54 ` Florian Weimer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAMe9rOphx_GcRh2vWp7mbNv8XiW1v+vaDF3RbN9hpDTYL2YYbQ@mail.gmail.com \
--to=hjl.tools@gmail.com \
--cc=Premachandra.Mallappa@amd.com \
--cc=fweimer@redhat.com \
--cc=gcc@gcc.gnu.org \
--cc=law@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=llvm-dev@lists.llvm.org \
--cc=matz@suse.de \
--cc=tstellar@redhat.com \
--cc=x86-64-abi@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).