From: "H.J. Lu" <hjl.tools@gmail.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: libc-alpha@sourceware.org, goldstein.w.n@gmail.com
Subject: Re: [PATCH v5 1/2] x86-64: Save APX and Tile registers in ld.so trampoline
Date: Thu, 15 Feb 2024 14:05:32 -0800 [thread overview]
Message-ID: <CAMe9rOoY7xjyZFySE4hUnmC2gPwXN11u1y+7w=nM19-aROQcnQ@mail.gmail.com> (raw)
In-Reply-To: <87bk8h8l0m.fsf@oldenburg.str.redhat.com>
On Thu, Feb 15, 2024 at 1:39 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Florian Weimer:
>
> > * H. J. Lu:
> >
> >> Add APX registers to STATE_SAVE_MASK so that APX and Tile registers are
> >> saved in ld.so trampoline. This fixes BZ #31371.
> >
> > First APX is confusing?
What do you suggest?
> >
> > What's the impact on xsave_state_size and xsave_state_full_size?
> > I'm worried that the loader trampoline now overflows small stacks.
> > We used to have such problems in the past.
>
> It adds 8,256 bytes on one AMX-capable machine. This will impact
> compatibility with existing software. Stack usage is increased even if
> the application does not use AMX at all.
Also AMX may be enabled much later.
> I suggest to use a mechanism like STO_AARCH64_VARIANT_PCS to deal with
> AMX, and only add the APX flag for now.
>
I will drop Tile registers.
--
H.J.
next prev parent reply other threads:[~2024-02-15 22:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-15 20:32 [PATCH v5 0/2] x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers H.J. Lu
2024-02-15 20:32 ` [PATCH v5 1/2] x86-64: Save APX and Tile registers in ld.so trampoline H.J. Lu
2024-02-15 21:26 ` Florian Weimer
2024-02-15 21:39 ` Florian Weimer
2024-02-15 22:05 ` H.J. Lu [this message]
2024-02-15 20:32 ` [PATCH v5 2/2] x86: Update _dl_tlsdesc_dynamic to preserve caller-saved registers H.J. Lu
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