From: Joseph Myers <joseph@codesourcery.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: <libc-alpha@sourceware.org>
Subject: Re: Why -static-libgcc? (Or: Do we need a build-time libc.so linker script?)
Date: Wed, 24 Nov 2021 23:19:29 +0000 [thread overview]
Message-ID: <alpine.DEB.2.22.394.2111242307250.1698965@digraph.polyomino.org.uk> (raw)
In-Reply-To: <87y25dmc7k.fsf@oldenburg.str.redhat.com>
On Wed, 24 Nov 2021, Florian Weimer via Libc-alpha wrote:
> Why do we use -static-libgcc? Doesn't this invalidate some of our
> tests, because users do not generally build with -static-libgcc?
There is a principle that (a) building glibc should not require a GCC
built with shared libgcc (to avoid circular dependencies, because building
shared libgcc requires having first built shared libc) and (b) if you
build glibc with a static-only C-only inhibit_libc GCC, the resulting
stripped binaries should be identical to those you get from a longer
alternating sequence of GCC and glibc builds (in particular, the binaries
should be identical to those you get from building with shared libgcc
available) (note that this requires appropriate use of
--with-glibc-version when configuring that first GCC in some cases - and
that, while I verified the "identical stripped binaries" property when
implementing --with-glibc-version and related glibc build fixes, I haven't
checked it recently and it's possible it could have regressed since 2013).
So building installed shared libraries needs to avoid any dependence on
shared libgcc (unless such dependence is handled in a way not requiring
shared libgcc to be available at build time - note that we know the
libgcc_s SONAME via shlib-versions, so if desired we could insert a
DT_NEEDED for it without using the real library, by building a dummy
shared library to link against or otherwise).
Testing is not expected to work fully with a static-only C-only
inhibit_libc GCC, so using the real shared libgcc in linking tests should
be OK (and desirable when the tests correspond to normal user code that
would end up linking with shared libgcc, on the general principle of
testing something as close as possible to how people would use installed
glibc).
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2021-11-24 23:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-24 22:16 Florian Weimer
2021-11-24 23:19 ` Joseph Myers [this message]
2022-01-10 13:00 ` Florian Weimer
2022-01-10 13:26 ` Adhemerval Zanella
2022-01-11 0:58 ` Joseph Myers
2022-04-19 11:57 ` Florian Weimer
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