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Re: [PATCH] x86: Don't remove empty x86 properties
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Cary Coutant <ccoutant at gmail dot com>, Binutils <binutils at sourceware dot org>
- Date: Tue, 27 Nov 2018 04:52:16 -0800
- Subject: Re: [PATCH] x86: Don't remove empty x86 properties
- References: <20181126214508.105748-1-hjl.tools@gmail.com> <CAJimCsHhUNTbMrO5uDfkaRVJSGz6QaJK3vBPbbpYGHE0mPirEA@mail.gmail.com>
On Mon, Nov 26, 2018 at 5:40 PM Cary Coutant <ccoutant@gmail.com> wrote:
>
> > Since empty x86 properties contain valid information, they shouldn't be
> > removed.
>
> Where is this documented? How is a property consisting of all zeroes
> different from a missing property?
>
> (I understand the difference for ISA_1_USED in relocatable objects --
> an input object missing this property kills the property for the
> output file -- but I can't find anything that says under what
> circumstances the output property section should contain a property
> with all zeroes.)
GNU_PROPERTY_X86_ISA_1_USED bits can be all zero when only
base x86 instructions are used. Linker shouldn't remove properties
with zero bits.
--
H.J.