From: Arnd Bergmann <arnd@arndb.de>
To: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
Kees Cook <keescook@chromium.org>,
linux-arch <linux-arch@vger.kernel.org>,
linux-kbuild <linux-kbuild@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Russell King <rmk+kernel@armlinux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
kernel-build-reports@lists.linaro.org,
kvmarm@lists.cs.columbia.edu
Subject: Re: [RFC] minimum gcc version for kernel: raise to gcc-4.3 or 4.6?
Date: Mon, 24 Apr 2017 22:30:52 +0200 [thread overview]
Message-ID: <CAK8P3a0HQUqtL=9pgPEreQJaA0AksiR06B4oAwvbYnJeA-2i7w@mail.gmail.com> (raw)
In-Reply-To: <alpine.LFD.2.20.1704241908260.32200@eddie.linux-mips.org>
On Mon, Apr 24, 2017 at 8:30 PM, Maciej W. Rozycki <macro@linux-mips.org> wrote:
> On Mon, 24 Apr 2017, Arnd Bergmann wrote:
>
>>
>> So it still fails, but only because of one compiler error that I can avoid by
>> disabling that driver, and you probably use a slightly patched compiler
>> version that doesn't have this particular bug, or it was a regression between
>> gcc-4.1.2 and 4.1.3.
>
> Umm, I didn't build modules, sorry, because I don't usually use them with
> those systems. However I have completed this step now and it also worked
> just fine:
>
> $ ls -la crypto/drbg.o
> -rw-r--r-- 1 macro macro 14096 Apr 24 18:59 crypto/drbg.o
> $ file crypto/drbg.o
> crypto/drbg.o: ELF 32-bit LSB MIPS-I relocatable, MIPS, version 1 (SYSV), not stripped
> $
>
> so you are likely right that either I have a patch applied to my 4.1.2
> build that has somehow fixed the ICE or it is a 4.1.3 regression (or a bad
> patch in your 4.1.3 build).
Ok.
> BTW I do see these `may be used uninitialized' warnings just as Geert
> does and even have a local patch, which I have neglected to submit, for a
> 64-bit configuration (`decstation_defconfig' is 32-bit) where in a single
> place -Werror turns it into a build failure. I do not consider it a big
> issue though, and might even wrap that patch up and submit sometime.
I'd recommend dropping that -Werror from mips and the other few
architectures that have it, or maybe wrapping it in a Kconfig symbol that
is disabled by default. It would also take care of
==> build/mips/bmips_be_defconfig/log <==
cc1: warnings being treated as errors
/git/arm-soc/arch/mips/bmips/setup.c:37: error: integer constant is
too large for 'long' type
As mentioned, we can also turn off the warnings by default and let
Geert turn them on again:
diff --git a/Makefile b/Makefile
index 779302695453..2528f60fb9ab 100644
--- a/Makefile
+++ b/Makefile
@@ -647,8 +647,10 @@ KBUILD_CFLAGS += -O2
endif
endif
-KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
- $(call
cc-disable-warning,maybe-uninitialized,))
+KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0408, \
+ $(call cc-disable-warning,uninitialized, \
+ $(call cc-ifversion, -lt, 0409, \
+ $(call
cc-disable-warning,maybe-uninitialized,))))
# Tell gcc to never replace conditional load with a non-conditional one
KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)
I've built the remaining defconfigs in the meantime (linux-4.11-rc8, gcc-4.1.3,
ARCH=mips) and got 38 builds with warnings and 20 failed builds. There are
at least six different build failures and only one ICE among them (only
in decstation_defconfig). With gcc-4.3 this is only slightly better: 18
failed build, 20 with warnings and 20 without warnings.
With linux-4.3, I saw this failure on 32 defconfigs,
and you fixed that in linux-4.7 with e49d38488515 ("MIPS: MSA: Fix a
link error on `_init_msa_upper' with older GCC"):
arch/mips/built-in.o: In function `enable_restore_fp_context':
traps.c:(.text+0xbefc): undefined reference to `_init_msa_upper'
traps.c:(.text+0xbfc0): undefined reference to `_init_msa_upper'
With gcc-4.9, all mips defconfigs now build without warnings.
For the other architectures in linux-4.11-rc8 can actually build with
sparc-gcc-4.1, afaict this was a bug that impacted all compilers up to
gcc-4.7 and a workaround was added recently. In turn, parisc-gcc-4.1
no longer works on linux-4.11, so we still have only three architectures
that can build their 'defconfig' with the old compiler, plus the majority
of the mips config files.
So while overall I still think that gcc-4.1 is rather broken, it seems that
you have it well under control on both mips and m68k. It's possible
that some other people use patched gcc-4.1 or only build special
configurations on further architectures that I found to be broken
with vanilla toolchains and the regular defconfig.
How about this approach then:
- To keep it simple, we update the README.rst to say that a minimum
gcc-4.3 is required, while recommending gcc-4.9 for all architectures
- Support for gcc-4.0 and earlier gets removed from linux/compiler.h,
and instead we add a summary of what I found, explaining that
gcc-4.1 has active users on a few architectures.
- We make the Makefile show a warning once during compilation for
gcc earlier than 4.3.
Arnd
next prev parent reply other threads:[~2017-04-24 20:30 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-16 10:56 [RFC] minimum gcc version for kernel: raise to gcc-4.3 or 4.6? Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 01/13] [HACK] gcc-4.5: avoid link errors for unused function pointers Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 02/13] KVM: arm: fix gcc-4.5 build Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2017-01-04 10:38 ` Christoffer Dall
2017-01-04 10:38 ` Christoffer Dall
2016-12-16 10:56 ` [PATCH 03/13] ARM: div64: fix building with gcc-4.5 and lower Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 04/13] vfio-pci: use 32-bit comparisons for register address for gcc-4.5 Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 15:30 ` Alex Williamson
2016-12-16 19:50 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 05/13] clk: pxa: fix gcc-4.4 build Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 06/13] ARM: atomic: " Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 07/13] watchdog: kempld: fix gcc-4.3 build Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 08/13] arm/arm64: xen: avoid gcc-4.4 warning Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 09/13] ARM: mark cmpxchg and xchg __always_inline for gcc-4.3 Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 10/13] asm-generic: mark cmpxchg as " Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 10:56 ` [PATCH 11/13] fs: fix unsigned enum warning with gcc-4.2 Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2017-01-03 22:47 ` Brendan Gregg
2017-02-28 21:53 ` Brendan Gregg
2016-12-16 10:56 ` [PATCH 12/13] KVM: arm: avoid binary number literals for gcc-4.2 Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2017-01-04 10:39 ` Christoffer Dall
2017-01-04 10:39 ` Christoffer Dall
2016-12-16 10:56 ` [PATCH 13/13] ARM: avoid 'Q' asm constraint for gcc-4.1 and earlier Arnd Bergmann
2016-12-16 10:56 ` Arnd Bergmann
2016-12-16 11:14 ` [RFC] minimum gcc version for kernel: raise to gcc-4.3 or 4.6? Arnd Bergmann
2016-12-16 11:14 ` Arnd Bergmann
2017-04-16 19:52 ` Kees Cook
2017-04-20 10:15 ` Arnd Bergmann
2017-04-20 19:52 ` Kees Cook
2017-04-20 19:52 ` Kees Cook
2017-04-21 20:55 ` Arnd Bergmann
2017-04-21 20:55 ` Arnd Bergmann
2017-04-21 21:05 ` Kees Cook
2017-04-21 21:05 ` Kees Cook
2017-04-22 3:10 ` Maciej W. Rozycki
2017-04-22 3:10 ` Maciej W. Rozycki
2017-04-22 15:30 ` Arnd Bergmann
2017-04-22 15:30 ` Arnd Bergmann
2017-04-23 20:13 ` Geert Uytterhoeven
2017-04-23 20:13 ` Geert Uytterhoeven
2017-04-24 9:44 ` Arnd Bergmann
2017-04-24 9:44 ` Arnd Bergmann
2017-04-24 10:17 ` Geert Uytterhoeven
2017-04-24 10:17 ` Geert Uytterhoeven
2017-04-24 14:13 ` Arnd Bergmann
2017-04-24 16:53 ` Maciej W. Rozycki
2017-04-24 17:29 ` Arnd Bergmann
2017-04-24 18:16 ` Geert Uytterhoeven
2017-04-24 18:16 ` Geert Uytterhoeven
2017-04-24 18:30 ` Maciej W. Rozycki
2017-04-24 18:30 ` Maciej W. Rozycki
2017-04-24 20:30 ` Arnd Bergmann [this message]
2017-04-24 20:52 ` Kees Cook
2017-04-25 7:06 ` Geert Uytterhoeven
2017-04-25 7:06 ` Geert Uytterhoeven
2017-04-25 9:22 ` Suzuki K Poulose
2017-04-25 9:22 ` Suzuki K Poulose
2016-12-16 15:54 ` Geert Uytterhoeven
2016-12-16 15:54 ` Geert Uytterhoeven
2016-12-16 19:58 ` Arnd Bergmann
2016-12-16 19:58 ` Arnd Bergmann
2016-12-16 20:34 ` Geert Uytterhoeven
2016-12-16 20:34 ` Geert Uytterhoeven
2016-12-16 17:00 ` Sebastian Andrzej Siewior
2016-12-16 22:00 ` Arnd Bergmann
2016-12-16 22:00 ` Arnd Bergmann
2016-12-17 11:29 ` Sebastian Andrzej Siewior
2016-12-17 11:29 ` Sebastian Andrzej Siewior
2017-01-02 12:23 ` Russell King - ARM Linux
2017-01-02 12:23 ` Russell King - ARM Linux
2016-12-20 9:59 ` Heiko Carstens
2016-12-20 9:59 ` Heiko Carstens
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