Re: [PATCH] arm: omap2: enable smc instruction for sleep34xx

[Dave Martin <dave.martin@linaro.org>]

On Tue, Apr 19, 2011 at 12:13:26PM +0200, "Anderö, Oskar" wrote:
> > > > Ping!
> > > >
> > > > Anyone else that gets bitten by the following when compiling
> > > omap2plus_defconfig with gcc 4.5:
> > > > arch/arm/mach-omap2/sleep34xx.S:150: Error: selected processor does
> > not
> > > support ARM mode `smc #1'
> > > >
> > > > -Oskar
> > > >
> > >
> > > I can report that I get the exact same compile error as this.
> > > OP patch worked beautifully.
> > >
> > > -Alex
> > 
> > Can you check what options are being passed to the compiler
> > and the assembler, and check for .arch / .arch_extension directives
> > in the assembler input?
> > 
> > i.e.,
> > 
> > make V=1 CFLAGS_KERNEL='-v -save-temps' arch/arm/mach-omap2/sleep34xx.o
> > 
> > ...and look at the output and the generated sleep34xx.s
> > 
> > Maybe the options being passed to the compiler/assembler are wrong
> > somewhere along the line.
> Yes, the "+sec" extension of armv7-a (i.e. -march=armv7-a+sec) is missing and hence the smc instruction can't be used. This is what my patch fixes. I guess earlier versions of binutils silently ignored this.
> 
> It's not visible in my patch, but plus_sec is declared as:
> plus_sec := $(call as-instr,.arch_extension sec,+sec)

Ah right, I was slightly confused by the context.

You're right -- sleep34xx.S also needs this change in the Makefile,
as per your patch.  This isn't new; the original patch focused on
omap4, so I guess this file was just missed.

Cheers
---Dave

> 
> The following patch added the same extension for some of the other files, but I guess sleep34xx.S was missed or maybe added later:
> commit fe297dde5ae8f8bf67d3a87759289a99b48ecb2c
> Author: John Rigby <john.rigby@linaro.org>
> Date:   Wed Dec 1 05:57:51 2010 +0000
> 
>     OMAP4: enable smc instruction in new assembler versions
>     
>     New assemblers need -march=armv7-a+sec on command line or
>     .arch_extension sec inline to enable use of the smc instruction.
> <snip>
> 
> -Oskar
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