On Sun, 21 Aug 2011, John Rigby wrote:
> I'm having trouble building the Thumb2 kernel on, I actually believe
> this same code worked some time ago before a toolchain update. There
> are actually two problems described below. I get past the first with
> a config change but don't know how to fix the second one.
>
[...]
> AS arch/arm/boot/compressed/head.o
> 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'
> make[2]: *** [arch/arm/boot/compressed/head.o] Error 1
> make[1]: *** [arch/arm/boot/compressed/vmlinux] Error 2
> make: *** [uImage] Error 2
>
> Here is my gcc version:
>
> $ arm-linux-gnueabi-gcc --version
> arm-linux-gnueabi-gcc (Ubuntu/Linaro 4.6.1-5ubuntu2~ppa1) 4.6.1
> Copyright (C) 2011 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>
> And as version:
> GNU assembler (GNU Binutils for Ubuntu) 2.21.52.20110707
> Copyright 2011 Free Software Foundation, Inc.
> This program is free software; you may redistribute it under the terms of
> the GNU General Public License version 3 or later.
> This program has absolutely no warranty.
> This assembler was configured for a target of `arm-linux-gnueabi'.
Looks to me like your assembler is broken, or gcc is not properly
telling it about the actual architecture in use.
To confirm, please try this:
echo -e ".arch armv7-a\n.thumb\nmrs r2, cpsr" | \
arm-linux-gnueabi-as - -o /dev/null
If that works then your assembler is fine. In that case the following
should fail:
echo -e ".thumb\nmrs r2, cpsr" | \
arm-linux-gnueabi-gcc -march=armv7-a -x assembler -o /dev/null -c -
If for some reasons this works too, then the kernel build might be
wrong. In that case, see the output of:
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- V=1 \
arch/arm/boot/compressed/head.o
I have:
arm-linux-gnueabi-gcc (Ubuntu/Linaro 4.5.2-8ubuntu3) 4.5.2
GNU assembler (GNU Binutils for Ubuntu) 2.21.0.20110327
And that works for me just fine.
Nicolas
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