Re: arm-uboot: misc.S:56: Error: r13 not allowed here -- `sub sp, fp, #4'

[Leif Lindholm]

On Wed, Nov 13, 2013 at 04:15:53PM +0100, Vladimir 'φ-coder/phcoder' Serbinenko 
wrote:
> On 13.11.2013 15:49, Colin Watson wrote:
> > After my previous fix, arm-uboot still fails to build with:
> > 
> >   arm-linux-gnueabihf-gcc -DHAVE_CONFIG_H -I. -I../../../grub-core -I..  
> > -Wall -W -I../../../include -I../include  -DGRUB_MACHINE_UBOOT=1 
> > -DGRUB_MACHINE_ARM=1 -DGRUB_MACHINE=ARM_UBOOT -DGRUB_TARGET_CPU_ARM=1 
> > -nostdinc -isystem /usr/lib/gcc-cross/arm-linux-gnueabihf/4.8/include 
> > -DGRUB_FILE=\"lib/arg.c\" -I. -I../../../grub-core -I.. -I../../.. 
> > -I../../../include -I../include 
> > -I../../../grub-core/lib/libgcrypt-grub/include 
> > -I../../../grub-core/lib/libgcrypt-grub/src/   -DGRUB_KERNEL=1   -Os -Wall 
> > -W -Wshadow -Wold-style-definition -Wpointer-arith -Wundef -Wextra 
> > -Wattributes -Wchar-subscripts -Wcomment -Wdeprecated-declarations 
> > -Wdisabled-optimization -Wdiv-by-zero -Wendif-labels -Wfloat-equal 
> > -Wformat-extra-args -Wformat-security -Wformat-y2k -Wimplicit 
> > -Wimplicit-function-declaration -Wimplicit-int -Winit-self 
> > -Wint-to-pointer-cast -Winvalid-pch -Wmain -Wmissing-braces 
> > -Wmissing-field-initializers -Wmissing-format-attribute -Wmultichar 
> > -Wnonnull -Woverflow -Wparentheses -Wpointer-ar
> ith -Wpointer-to-int-cast -Wreturn-type -Wsequence-point -Wshadow 
> -Wsign-compare -Wstrict-aliasing -Wswitch -Wtrigraphs -Wundef 
> -Wunknown-pragmas -Wunused -Wunused-function -Wunused-label 
> -Wunused-parameter -Wunused-value  -Wunused-variable -Wvariadic-macros 
> -Wvolatile-register-var -Wwrite-strings -Wnested-externs -Wstrict-prototypes 
> -Wpointer-sign -g -Wredundant-decls -Wmissing-prototypes 
> -Wmissing-declarations -Wcast-align -freg-struct-return -fno-dwarf2-cfi-asm 
> -fno-asynchronous-unwind-tables -fno-stack-protector -mno-unaligned-access 
> -Wtrampolines -Werror -DUSE_ASCII_FALLBACK=1 -DHAVE_UNIFONT_WIDTHSPEC=1     
> -mthumb-interwork -mlong-calls -ffreestanding   -MT lib/kernel_exec-arg.o -MD 
> -MP -MF lib/.deps-core/kernel_exec-arg.Tpo -c -o lib/kernel_exec-arg.o `test 
> -f 'lib/arg.c' || echo '../../../grub-core/'`lib/arg.c
> >   misc.S: Assembler messages:
> >   misc.S:56: Error: r13 not allowed here -- `sub sp,fp,#4'
> >   make[3]: *** [kern/arm/kernel_exec-misc.o] Error 1
> > 
> > I don't think SP can be used that way in Thumb mode?
> > 
> I think that our asm routines should be in full ARM. Attached patch
> follows this strategy. One remaining problem is to make sure that thumb
> flags in TARGET_CFLAGS and TARGET_CCASFLAGS match.

There should be no need for this - the only thing is to ensure the
-mthumb-interwork is set in CCASFLAGS_PLATFORM as well as
CFLAGS_PLATFORM, and even that is just to prevent linker warnings..

There is no special ARM_PROLOGUE needed, and (on armv5te onwards)
pop {..., pc} is an interworking branch.

If we want to force a file to build as ARM (which I'm not sure is
necessary now that we have split up armv6 separate from later
architectures), all that is required is a .arm directive up top.

/
    Leif