Re: [PATCH soc] ARM: use ARM_SINGLE_ARMV7M for ARMv7-M platforms

From: Maxime Coquelin
Date: Fri May 22 2015 - 11:29:26 EST


2015-05-22 16:50 GMT+02:00 Arnd Bergmann <arnd@xxxxxxxx>:
> [one small request as I have four armv7-m folks on Cc already:
> could one of you try to fix the warning that I get with every
> single build: "/git/arm-soc/arch/arm/kernel/head-nommu.S: Assembler
> messages: /git/arm-soc/arch/arm/kernel/head-nommu.S:167: Warning:
> Use of r13 as a source register is deprecated when r15 is the
> destination register."]

Moving r13 to r12 and returning r12 seems to do the job (see below).
But I don't know if there is a more elegant way, and if it is also
valid for other architectures than armv7-m.
I can propose a patch if someone can confirm it is valid.

Regards,
Maxime

-------------------------------------------------------------------------------------------------------------

diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S
index aebfbf7..e84bdad 100644
--- a/arch/arm/kernel/head-nommu.S
+++ b/arch/arm/kernel/head-nommu.S
@@ -164,7 +164,8 @@ __after_proc_init:
#endif
mcr p15, 0, r0, c1, c0, 0 @ write control reg
#endif /* CONFIG_CPU_CP15 */
- ret r13
+ mov r12, r13
+ ret r12
ENDPROC(__after_proc_init)
.ltorg
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