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From: David Laight <David.Laight@ACULAB.COM>
To: 'Arvind Sankar' <nivedita@alum.mit.edu>,
	Nick Desaulniers <ndesaulniers@google.com>
Cc: Will Deacon <will@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"kernel-team@android.com" <kernel-team@android.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"Peter Zijlstra" <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Segher Boessenkool <segher@kernel.crashing.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Peter Oberparleiter <oberpar@linux.ibm.com>,
	Masahiro Yamada <masahiroy@kernel.org>
Subject: RE: [PATCH v2 00/10] Rework READ_ONCE() to improve codegen
Date: Fri, 24 Jan 2020 10:11:03 +0000
Message-ID: <a9d4a3c113ed4f09897477d3a9be1f84@AcuMS.aculab.com> (raw)
In-Reply-To: <20200123190125.GA2683468@rani.riverdale.lan>

From: Arvind Sankar
> Sent: 23 January 2020 19:01
...
> > > Oh - and I need to find a newer compiler :-(
> >
> > What distro are you using? Does it have a package for a newer
> > compiler?  I'm honestly curious about what policies if any the kernel
> > has for supporting developer's toolchains from their distributions.

Like many developers I get lazy with upgrades of some systems.
So my main Linux 'desktop' system is running Ubuntu 13.04 userspace
with a very recent kernel.
So it has gcc 4.7.3 as default and a gcc 4.8.1 installed (probably not mature
enough to be safe!).
(I've 2 other i7 systems running Ubuntu 18.04.0x with the distro kernels.)
...
> I think the issue is not just kernel devs. Users may need to compile a
> custom kernel or at least build a module.

If they are just building a module they'll be using the kernel headers
that go with the distro kernel - and the module sources will need to
match. So the distro's gcc should match.

Much more interesting is the gcc compiler we use to generate the
'binary blob' for our 'out of tree' drivers.
These get compiled (without any of the kernel headers) on the
same system as we build the userspace programs on.
To get libc and (especially) libc++ compatibility this has to be
a very old system - as old as the oldest system any of our
customers are likely to use.
In practise this (now) means something running a 2.6.32 era
kernel (or slightly earlier).
So is a debian gcc 4.3.2-1.1 compiler.
I think we've finally persuaded all our customers to upgrade from 2.6.18.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  reply index

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-23 15:33 Will Deacon
2020-01-23 15:33 ` [PATCH v2 01/10] compiler/gcc: Emit build-time warning for GCC prior to version 4.8 Will Deacon
2020-01-23 15:33 ` [PATCH v2 02/10] netfilter: Avoid assigning 'const' pointer to non-const pointer Will Deacon
2020-01-23 19:07   ` Nick Desaulniers
2020-01-24  8:24     ` Peter Zijlstra
2020-01-24 17:20       ` Nick Desaulniers
2020-01-27 12:04         ` David Laight
2020-01-24 17:36       ` Linus Torvalds
2020-01-24 22:00         ` Peter Zijlstra
2020-01-27 12:21         ` David Laight
2020-01-23 15:33 ` [PATCH v2 03/10] fault_inject: Don't rely on "return value" from WRITE_ONCE() Will Deacon
2020-01-23 15:33 ` [PATCH v2 04/10] READ_ONCE: Simplify implementations of {READ,WRITE}_ONCE() Will Deacon
2020-01-23 15:33 ` [PATCH v2 05/10] READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses Will Deacon
2020-01-25  8:27   ` Peter Zijlstra
2020-01-29 10:49     ` Peter Zijlstra
2020-01-23 15:33 ` [PATCH v2 06/10] READ_ONCE: Drop pointer qualifiers when reading from scalar types Will Deacon
2020-01-23 15:33 ` [PATCH v2 07/10] locking/barriers: Use '__unqual_scalar_typeof' for load-acquire macros Will Deacon
2020-01-23 15:33 ` [PATCH v2 08/10] arm64: barrier: Use '__unqual_scalar_typeof' for acquire/release macros Will Deacon
2020-01-23 15:33 ` [PATCH v2 09/10] compiler/gcc: Raise minimum GCC version for kernel builds to 4.8 Will Deacon
2020-01-23 18:36   ` Nick Desaulniers
2020-01-24  8:26     ` Peter Zijlstra
2020-01-24 17:05       ` Nick Desaulniers
2020-01-24 23:29         ` Peter Zijlstra
2020-01-25 10:34         ` Michael Ellerman
2020-01-23 15:33 ` [PATCH v2 10/10] gcov: Remove old GCC 3.4 support Will Deacon
2020-01-23 18:51   ` Nick Desaulniers
2020-01-28 14:56   ` Peter Oberparleiter
2020-01-23 17:07 ` [PATCH v2 00/10] Rework READ_ONCE() to improve codegen David Laight
2020-01-23 17:16   ` Will Deacon
2020-01-23 17:32     ` David Laight
2020-01-23 18:45       ` Nick Desaulniers
2020-01-23 19:01         ` Arvind Sankar
2020-01-24 10:11           ` David Laight [this message]
2020-01-26  1:10           ` Qais Yousef
2020-01-27  7:26             ` Arnd Bergmann
2020-01-23 17:59 ` Linus Torvalds
2020-01-24  8:33   ` Peter Zijlstra
2020-01-24 10:41     ` Peter Zijlstra
2020-02-10  9:50     ` Masahiro Yamada
2020-02-10  9:59       ` Will Deacon
2020-01-31 10:20 ` David Howells

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