From: "H.J. Lu" <hjl.tools@gmail.com>
To: Joseph Myers <joseph@codesourcery.com>
Cc: GNU C Library <libc-alpha@sourceware.org>,
Binutils <binutils@sourceware.org>
Subject: Re: [PATCH v2] elf: Support DT_RELR relative relocation format [BZ #27924]
Date: Mon, 18 Oct 2021 18:05:18 -0700 [thread overview]
Message-ID: <CAMe9rOprHXNZgLqAtP44kM5e_C7COv367tFoKXUmqWs0eaQPpQ@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2110182339050.139834@digraph.polyomino.org.uk>
On Mon, Oct 18, 2021 at 4:44 PM Joseph Myers <joseph@codesourcery.com> wrote:
>
> On Mon, 18 Oct 2021, H.J. Lu via Libc-alpha wrote:
>
> > Ideally when the new specifiers are used, it should require the new
> > glibc version. Is there a way to do it?
>
> I don't think there's any sensible way to do it. You'd need new symbol
> versions (aliased to the old ones, not actual separate entry points with
> different addresses) for all the 70 or so printf-like functions (twice
> that number when two long double variants are supported, three times that
> number when three long double variants are supported). That's not
> something we've done before for new printf/scanf/strftime/strfmon formats.
>
> The scanf changes will get new __isoc23_* entry points because of API
> differences with scanf %i (but someone could still e.g. use scanf %b when
> building for strict C11, and so get a binary using the old entry point
> with a new format that doesn't work with older glibc - there would only be
> the 32 / 44 / 56 new entry points, not new symbol versions for old entry
> points).
>
On glibc 2.34 machine:
[hjl@gnu-snb-1 tmp]$ cat x.c
#include <stdio.h>
int
main ()
{
printf ("hello\n");
return 0;
}
[hjl@gnu-snb-1 tmp]$ cat v.S
.section .data.retain,"awR",%progbits
.dc.a GLIBC_2.34
[hjl@gnu-snb-1 tmp]$ gcc v.S x.c
[hjl@gnu-snb-1 tmp]$ ./a.out
hello
[hjl@gnu-snb-1 tmp]$
Copy it to glibc 2.33 machine:
[hjl@gnu-cfl-1 tmp]$ ./a.out
./a.out: /lib64/libc.so.6: version `GLIBC_2.34' not found (required by ./a.out)
[hjl@gnu-cfl-1 tmp]$
Does glibc built by lld have glibc versions in the dynamic symbol table?
If not, lld can't be used to generate glibc.
--
H.J.
next prev parent reply other threads:[~2021-10-19 1:05 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-17 0:50 Fangrui Song
2021-10-18 14:42 ` H.J. Lu
2021-10-18 16:16 ` Fāng-ruì Sòng
2021-10-18 17:28 ` H.J. Lu
2021-10-18 18:15 ` Fāng-ruì Sòng
2021-10-18 18:27 ` H.J. Lu
2021-10-18 19:19 ` Fāng-ruì Sòng
2021-10-18 19:44 ` H.J. Lu
2021-10-18 20:11 ` Fāng-ruì Sòng
2021-10-18 21:10 ` Joseph Myers
2021-10-18 22:27 ` H.J. Lu
2021-10-18 22:30 ` Joseph Myers
2021-10-18 22:42 ` H.J. Lu
2021-10-18 23:00 ` Joseph Myers
2021-10-18 23:36 ` H.J. Lu
2021-10-18 23:44 ` Joseph Myers
2021-10-19 1:05 ` H.J. Lu [this message]
2021-10-18 19:21 ` Joseph Myers
2021-10-18 19:45 ` H.J. Lu
2021-10-29 18:21 ` Carlos O'Donell
2021-10-29 18:36 ` H.J. Lu
2021-10-29 19:15 ` Fangrui Song
2021-10-29 18:38 ` Fāng-ruì Sòng
2021-10-29 19:35 ` Carlos O'Donell
2021-10-29 19:53 ` Adhemerval Zanella
2021-11-01 4:50 ` Fāng-ruì Sòng
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