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Re: [PATCH] x86: document certain command line options as "dangerous"
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Jan Beulich <JBeulich at suse dot com>
- Cc: Binutils <binutils at sourceware dot org>
- Date: Mon, 24 Jun 2019 09:21:01 -0700
- Subject: Re: [PATCH] x86: document certain command line options as "dangerous"
- References: <5D10D50E020000780023AA78@prv1-mh.provo.novell.com>
On Mon, Jun 24, 2019 at 6:50 AM Jan Beulich <JBeulich@suse.com> wrote:
>
> Errata BT36, BT41, and BT230 mean that gas may, when using one ofthese
> options, produce code that causes #UD on (at least) SandyBridge systems.
>
> gas/
> 2019-06-24 Jan Beulich <jbeulich@suse.com>
>
> * doc/c-i386.texi: Mark -mavxscalar= and -mvexwig as dangrous to
> use.
>
> --- a/gas/doc/c-i386.texi
> +++ b/gas/doc/c-i386.texi
> @@ -303,6 +303,9 @@ AVX instructions with 128bit vector leng
> @option{-mavxscalar=@var{256}} will encode scalar AVX instructions
> with 256bit vector length.
>
> +WARNING: Don't use this for production code - due to CPU errata the
> +resulting code may not work on certain models.
> +
> @cindex @samp{-mvexwig=} option, i386
> @cindex @samp{-mvexwig=} option, x86-64
> @item -mvexwig=@var{0}
> @@ -313,6 +316,9 @@ instructions with vex.w = 0, which is th
> @option{-mvexwig=@var{1}} will encode WIG EVEX instructions with
> vex.w = 1.
>
> +WARNING: Don't use this for production code - due to CPU errata the
> +resulting code may not work on certain models.
> +
> @cindex @samp{-mevexlig=} option, i386
> @cindex @samp{-mevexlig=} option, x86-64
> @item -mevexlig=@var{128}
>
OK.
Thanks.
--
H.J.