From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: makefile: work around toolchain bug in recent versions of binutils
Date: Thu, 2 Aug 2012 16:01:23 +0100 [thread overview]
Message-ID: <20120802150123.GE9838@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <20120802130411.GU6802@n2100.arm.linux.org.uk>
Hi Russell,
On Thu, Aug 02, 2012 at 02:04:11PM +0100, Russell King - ARM Linux wrote:
> On Thu, Aug 02, 2012 at 01:23:26PM +0100, Will Deacon wrote:
> > Recent upstream versions of binutils fail to assembler compressed/head.S
> > when passed the -march=all option:
> >
> > http://lists.gnu.org/archive/html/bug-binutils/2011-04/msg00162.html
> >
> > The recommended workaround from the tools folks is not to pass the
> > option, and instead let the assembler deduce the CPU type based on the
> > features used by the code.
>
> That doesn't work for all binutils - binutils historically has had to be
> told explicitly what architecture its building for and won't "deduce"
> it from the code.
Damn. I thought there would be a reason why we passed the option in the
first place.
> Maybe this needs to be a build-time test whether the assembler accepts it?
That could be tricky since gas still accepts the option, but fails later
with:
arch/arm/boot/compressed/head.S: Assembler messages:
arch/arm/boot/compressed/head.S:127: Error: selected processor does not support requested special purpose register -- `mrs r2,cpsr'
arch/arm/boot/compressed/head.S:134: Error: selected processor does not support requested special purpose register -- `mrs r2,cpsr'
arch/arm/boot/compressed/head.S:136: Error: selected processor does not support requested special purpose register -- `msr cpsr_c,r2'
How about grabbing the march from KBUILD_AFLAGS instead (see below)?
Will
---8<---
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index bb26756..3774f0d 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -126,7 +126,7 @@ KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS))
endif
ccflags-y := -fpic -fno-builtin -I$(obj)
-asflags-y := -Wa,-march=all
+asflags-y := -Wa,$(lastword $(filter -march=%,$(KBUILD_AFLAGS)))
# Supply kernel BSS size to the decompressor via a linker symbol.
KBSS_SZ = $(shell $(CROSS_COMPILE)size $(obj)/../../../../vmlinux | \
next prev parent reply other threads:[~2012-08-02 15:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-02 12:23 [PATCH] ARM: makefile: work around toolchain bug in recent versions of binutils Will Deacon
2012-08-02 13:04 ` Russell King - ARM Linux
2012-08-02 15:01 ` Will Deacon [this message]
2012-08-02 15:30 ` Russell King - ARM Linux
2012-08-02 15:51 ` Will Deacon
2012-08-02 18:18 ` Russell King - ARM Linux
2012-08-02 18:50 ` Will Deacon
2012-08-02 19:09 ` Arnaud Patard (Rtp)
2012-08-02 19:44 ` Russell King - ARM Linux
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