From: Fangrui Song <i@maskray.me>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Nick Clifton <nickc@redhat.com>, Binutils <binutils@sourceware.org>
Subject: Re: [PATCH] elf: Also check linked-to section for SHT_NOTE section
Date: Wed, 30 Sep 2020 20:41:59 -0700 [thread overview]
Message-ID: <MWHPR12MB1456FF73D980368A3F822F31CB300@MWHPR12MB1456.namprd12.prod.outlook.com> (raw)
In-Reply-To: <CAMe9rOo-Nz6vt3ue2z0+iQNXCx6AkqyjSzN=ZghWCFdsTpPpEw@mail.gmail.com>
On Wed, Sep 30, 2020 at 7:03 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Wed, Sep 30, 2020 at 7:01 AM Nick Clifton <nickc@redhat.com> wrote:
> >
> > Hi H.J.
> >
> > Thanks for taking an interest in this.
> >
> > > Please try this patch.
> > It did not appear to make a difference. :-(
> >
> > I am using an extended test case (attached) but the results are the
> > same as before:
> >
> > % as eliminate.s -o eliminate.o
> > % ld -e 0 --gc-sections --print-gc-sections eliminate.o
> > ld: removing unused section '.group' in file 'eliminate.o'
> > ld: removing unused section '.group' in file 'eliminate.o'
> > ld: removing unused section '.text' in file 'eliminate.o'
> > ld: removing unused section '.unused1' in file 'eliminate.o'
> > ld: removing unused section '.unused2[unused_group]' in file 'eliminate.o'
> > ld: removing unused section '.unused3[unused_group2]' in file 'eliminate.o'
> > ld: removing unused section '.gnu.note2[unused_group]' in file 'eliminate.o'
> > ld: removing unused section '.gnu.note3[unused_group2]' in file 'eliminate.o'
> > ld: a.out: sh_link of section `.gnu.note1' points to discarded section `.unused1' of `eliminate.o'
> > ld: final link failed: bad value
> >
> > Cheers
> > Nick
>
> Works for me:
>
> [hjl@gnu-cfl-2 ld]$ gcc -c eliminate.s
> [hjl@gnu-cfl-2 ld]$ ./ld-new -e 0 --gc-sections --print-gc-sections eliminate.o
> ./ld-new: removing unused section '.group' in file 'eliminate.o'
> ./ld-new: removing unused section '.group' in file 'eliminate.o'
> ./ld-new: removing unused section '.text' in file 'eliminate.o'
> ./ld-new: removing unused section '.unused1' in file 'eliminate.o'
> ./ld-new: removing unused section '.unused2[unused_group]' in file 'eliminate.o'
> ./ld-new: removing unused section '.unused3[unused_group2]' in file
> 'eliminate.o'
> ./ld-new: removing unused section '.gnu.note1' in file 'eliminate.o'
> ./ld-new: removing unused section '.gnu.note2[unused_group]' in file
> 'eliminate.o'
> ./ld-new: removing unused section '.gnu.note3[unused_group2]' in file
> 'eliminate.o'
> [hjl@gnu-cfl-2 ld]$
>
>
> --
> H.J.
Thanks HJ for the patch. The --gc-sections semantics I expect are
written down here:
https://sourceware.org/pipermail/binutils/2020-February/109851.html
(If SHF_GNU_RETAIN
(https://sourceware.org/pipermail/binutils/2020-September/113534.html)
is accepted, a SHF_GNU_RETAIN section will be added to the GC root
list.
I forwarded the progress to a few toolchain folks on LLVM side and
encouraged them to reply if they still have concerns.)
prev parent reply other threads:[~2020-10-01 3:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 15:12 RFC: New gas directive: .attach_to_group Nick Clifton
2020-09-29 16:53 ` Fangrui Song
2020-09-30 9:33 ` Nick Clifton
[not found] ` <3609c590-8750-a021-92fb-05ff0ba7ca7d@redhat.com>
2020-09-30 13:43 ` [PATCH] elf: Also check linked-to section for SHT_NOTE section H.J. Lu
2020-09-30 14:01 ` Nick Clifton
2020-09-30 14:03 ` H.J. Lu
2020-10-01 3:41 ` Fangrui Song [this message]
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