From: David Laight <David.Laight@ACULAB.COM>
To: 'Arnd Bergmann' <arnd@arndb.de>,
Matthew Wilcox <willy@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Segher Boessenkool <segher@kernel.crashing.org>,
Joe Perches <joe@perches.com>,
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Albert Ou <aou@eecs.berkeley.edu>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jonathan Corbet <corbet@lwn.net>,
"Linux Doc Mailing List" <linux-doc@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
"Paul Walmsley" <paul.walmsley@sifive.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Miguel Ojeda <ojeda@kernel.org>,
Paul Mackerras <paulus@samba.org>,
linux-riscv <linux-riscv@lists.infradead.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Will Deacon <will@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH] Raise the minimum GCC version to 5.2
Date: Mon, 3 May 2021 12:20:45 +0000 [thread overview]
Message-ID: <fc0c7c092f274ab8b760b3c897830347@AcuMS.aculab.com> (raw)
In-Reply-To: <CAK8P3a0kV4ZfMEFh0DcMDjXqxA0yhj8a8CL-YFGV6B4pszHeGg@mail.gmail.com>
From: Arnd Bergmann
> Sent: 03 May 2021 10:25
...
> One scenario that I've seen previously is where user space and
> kernel are built together as a source based distribution (OE, buildroot,
> openwrt, ...), and the compiler is picked to match the original sources
> of the user space because that is best tested, but the same compiler
> then gets used to build the kernel as well because that is the default
> in the build environment.
If you are building programs for release to customers who might
be running then on old distributions then you need a system with
the original userspace headers and almost certainly a similar
vintage compiler.
Never mind RHEL7 we have customers running RHEL6.
(We've managed to get everyone off RHEL5.)
So the build machine is running a 10+ year old distro.
I did try to build on a newer system (only 5 years old)
but the complete fubar of memcpy() makes it impossible
to compile C programs that will run on an older libc.
And don't even mention C++, the 'character traits' is just
plain horrid - enough to make me want to remove every
reference to CString from the small amount of C++ we have.
To quote our makefile:
# C++ is fighting back.
# I'd like to be able to compile on a 'new' system and still be able to run
# the binaries on RHEL 6 (2.6.32 kernel 2011 era libraries).
# But even linking libstdc++ static still leaves
# an undefined C++ symbol that the dynamic loader barfs on.
# The static libstdc++ also references memcpy@GLIBC_2.14 - but that can be
# 'solved' by adding an extra .so that defines the symbol (and calls memmove()).
# I've also tried pulling a single .o out of libstc++.a. This might work if
# the .o is small and self contained.
#
# For now we statically link libstc++ and continue to build on an old system.
C++LDLIBS := -Wl,-Bstatic -lstdc++ -Wl,-Bdynamic
It would be nice to be able to build current kernels (for local
use) on the 'new' system - but gcc is already too old.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
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next prev parent reply other threads:[~2021-05-03 12:23 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-01 15:15 [PATCH] Raise the minimum GCC version to 5.2 Masahiro Yamada
2021-05-01 15:52 ` Miguel Ojeda
2021-05-01 17:38 ` Christophe Leroy
2021-05-02 2:41 ` Joe Perches
2021-05-02 18:30 ` Segher Boessenkool
2021-05-02 20:00 ` Joe Perches
2021-05-02 20:32 ` Segher Boessenkool
2021-05-02 21:05 ` Ali Kaasinen
2021-05-02 21:08 ` Linus Torvalds
2021-05-02 22:30 ` Matthew Wilcox
2021-05-03 7:34 ` Alexander Dahl
2021-05-03 8:54 ` Joe Perches
2021-05-03 9:25 ` Arnd Bergmann
2021-05-03 12:20 ` David Laight [this message]
2021-05-03 13:10 ` Miguel Ojeda
2021-05-04 5:30 ` Alexander Dahl
2021-05-04 6:33 ` Christophe Leroy
2021-05-04 12:07 ` Arnd Bergmann
2021-05-04 13:25 ` Andy Shevchenko
2021-05-03 11:35 ` Arnd Bergmann
2021-05-03 9:49 ` Kirill A. Shutemov
2021-05-02 21:23 ` Joe Perches
2021-05-03 0:44 ` Segher Boessenkool
2021-05-03 9:57 ` Arnd Bergmann
2021-05-04 7:56 ` Ben Dooks
2021-05-04 8:38 ` Miguel Ojeda
2021-05-04 9:22 ` Michal Suchánek
2021-05-04 12:09 ` Miguel Ojeda
2021-05-04 12:17 ` Michal Suchánek
2021-05-04 12:26 ` Christophe Leroy
2021-05-02 18:37 ` Segher Boessenkool
2021-05-03 6:16 ` Christophe Leroy
2021-05-04 2:13 ` Masahiro Yamada
2021-05-04 13:18 ` Andy Shevchenko
2021-05-03 12:27 ` David Sterba
2021-05-15 7:14 ` Pavel Machek
2021-05-15 7:27 ` Joe Perches
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