[U-Boot-Users] [bug] arm920t start.S fails to compile with large CFG_MALLOC_LEN

[Andrew Dyer]

In cpu/arm920t/start.S the macro get_bad_stack assumes that
(CONFIG_STACKSIZE+CFG_MALLOC_LEN) will fit in a 16-bit constant.  I am
trying to do a build where CFG_MALLOC_LEN is much larger (need
buffering for gzip splash screen decompression).  Assembly of the file
fails with errors due to invalid constants.

make[1]: Entering directory `/home/adyer/Projects/u-boot/cpu/arm920t'
arm-linux-gcc  -D__ASSEMBLY__ -g  -Os   -fno-strict-aliasing
-fno-common -ffixed-r8 -msoft-float  -D__KERNEL__
-DTEXT_BASE=0x0bd80000  -I/home/adyer/Projects/u-boot/include
-fno-builtin -ffreestanding -nostdinc -isystem
/home/adyer/usr/bin/../lib/gcc/arm-linux/4.0.0/include -pipe
-DCONFIG_ARM -D__ARM__ -march=armv4 -mabi=apcs-gnu -c -o start.o
start.S
start.S: Assembler messages:
start.S:375: Error: invalid constant -- `sub r13,r13,#((120<<10)+(4<<20))'
start.S:376: Error: invalid constant -- `sub r2,r2,#((120<<10)+(4<<20))'
start.S:381: Error: invalid constant -- `sub r13,r13,#((120<<10)+(4<<20))'
start.S:382: Error: invalid constant -- `sub r2,r2,#((120<<10)+(4<<20))'
start.S:387: Error: invalid constant -- `sub r13,r13,#((120<<10)+(4<<20))'
start.S:388: Error: invalid constant -- `sub r2,r2,#((120<<10)+(4<<20))'
start.S:393: Error: invalid constant -- `sub r13,r13,#((120<<10)+(4<<20))'
start.S:394: Error: invalid constant -- `sub r2,r2,#((120<<10)+(4<<20))'
start.S:399: Error: invalid constant -- `sub r13,r13,#((120<<10)+(4<<20))'
start.S:400: Error: invalid constant -- `sub r2,r2,#((120<<10)+(4<<20))'
start.S:424: Error: invalid constant -- `sub r13,r13,#((120<<10)+(4<<20))'
start.S:425: Error: invalid constant -- `sub r2,r2,#((120<<10)+(4<<20))'
start.S:430: Error: invalid constant -- `sub r13,r13,#((120<<10)+(4<<20))'
start.S:431: Error: invalid constant -- `sub r2,r2,#((120<<10)+(4<<20))'
make[1]: *** [start.o] Error 1
make[1]: Leaving directory `/home/adyer/Projects/u-boot/cpu/arm920t'
make: *** [cpu/arm920t/libarm920t.a] Error 2

the macro looks like this:

        .macro get_bad_stack
        ldr     r13, _armboot_start             @ setup our mode stack
        sub     r13, r13, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)
        sub     r13, r13, #(CFG_GBL_DATA_SIZE+8)

        str     lr, [r13]                       @ save caller lr / spsr
        mrs     lr, spsr
        str     lr, [r13, #4]

        mov     r13, #MODE_SVC                  @ prepare SVC-Mode
        @ msr   spsr_c, r13
        msr     spsr, r13
        mov     lr, pc
        movs    pc, lr
        .endm

It looks like this macro is called from an exception context. I'm an
ARM newbie, so I'm looking for some help.  What registers are safe to
use in this context so I can calculate a good stack location?  Any
other ideas on how to get around this?

-- 
Hardware, n.:
        The parts of a computer system that can be kicked.