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Re: RFC: Add PT_GNU_PROPERTY to cover .note.gnu.property section
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Mark Wielaard <mark at klomp dot org>
- Cc: Cary Coutant <ccoutant at gmail dot com>, Florian Weimer <fweimer at redhat dot com>, Binutils <binutils at sourceware dot org>, GNU C Library <libc-alpha at sourceware dot org>, gnu-gabi at sourceware dot org, x86-64-abi <x86-64-abi at googlegroups dot com>
- Date: Wed, 12 Dec 2018 04:58:47 -0800
- Subject: Re: RFC: Add PT_GNU_PROPERTY to cover .note.gnu.property section
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On Wed, Dec 12, 2018 at 2:44 AM Mark Wielaard <email@example.com> wrote:
> On Tue, Dec 11, 2018 at 09:58:30PM -0800, Cary Coutant wrote:
> > > > I would strongly recommended to try harder to get consensus here. I do
> > > > not want to be a in a situation were we revise ABI again two years from
> > > > now.
> > >
> > > That is my hope. PT_GNU_PROPERTY is our consensus so far.
> > As you might expect, I support this new program header. Ideally, I'd
> > have liked to replace the input SHT_NOTE sections with
> > SHT_GNU_PROPERTY sections and dispense with all the note section
> > overhead, but I'll take this as a compromise.
> Why can't we switch to SHT_GNU_PROPERTY? My fear with combining
> PT_GNU_PROPERTY with SHT_NOTE is that it will be even more confusing
There is no requirement for PT_XXX to have SHT_XXX, like PT_GNU_RELRO.
> for tools. You will get some allocated SHT_NOTEs in a PT_NOTE segment
> and others in this new PT_GNU_PROPERTY segment (or worse, you get
> multiple segments with different types covering the same ranges).
It is normal to have multiple segments to cover the same section,
like PT_TLS and PT_GNU_RELRO.
> Also I thought there was still a question whether any or all
> newly proposed property features and flags are actually needed
> as loadable segments. There is a clear overlap with the GNU
> Attributes (which are non-loadable). I would like to see consensus
> first on the new property format/flags and which are and which
> aren't needed as loadable properties at runtime.
Yes, they are needed in loadable segment. That is the main motivation
for GNU program property,