> I've just built an assembler/linker with the options you mention.
>
> Compiling the following testcase:
>
> .text
> .arm
> .cpu arm7tdmi
> .global _start
> .type _start, %function
> _start:
> bl bar
> bx lr
> .thumb
> .global bar
> .type bar, %function
> bar:
> bx lr
>
> Results in:
>
> .../as /tmp/asm.s -o /tmp/asm.o
> .../ld -o /tmp/asm /tmp/asm.o
>
> .../objdump -d /tmp/asm
>
> /tmp/asm: file format elf32-littlearm
>
>
> Disassembly of section .text:
>
> 00008000 <_start>:
> 8000: eb000002 bl 8010 <__bar_from_arm>
> 8004: e12fff1e bx lr
>
> 00008008 <bar>:
> 8008: 4770 bx lr
> 800a: 46c0 nop ; (mov r8,
> r8)
> 800c: 0000 movs r0, r0
> ...
>
> 00008010 <__bar_from_arm>:
> 8010: e59fc000 ldr ip, [pc] ; 8018
> <__bar_from_arm+0x8>
> 8014: e12fff1c bx ip
> 8018: 00008009 .word 0x00008009
> 801c: 00000000 .word 0x00000000
>
> Change the .cpu directive to
> .cpu cortex-a9
> and you get
>
> objdump -d /tmp/asm
>
> /tmp/asm: file format elf32-littlearm
>
>
> Disassembly of section .text:
>
> 00008000 <_start>:
> 8000: fa000000 blx 8008 <bar>
> 8004: e12fff1e bx lr
>
> 00008008 <bar>:
> 8008: 4770 bx lr
> 800a: bf00 nop
>
>
> So exactly how are you calling the linker?
The original example I was trying to debug was u-boot, which is a complicated
example because it uses a custom linker script and it's own libgcc, but using
your "readelf -A" hint I was able to track down that some of my objects were
compiled armv5.
I also created a simple 2 function test in C
$ cat main.c
void main(void);
int arm_incr(int x);
void main(void) { int x = arm_incr(2); }
$ cat arm.c
int arm_incr(int x) { return x + 1; }
$ arm-cortex_a9-linux-gnueabi-gcc -mcpu=arm7tdmi -march=armv4t
-mthumb-interwork -mthumb -c -o main.o main.c
$ arm-cortex_a9-linux-gnueabi-gcc -mcpu=arm7tdmi -march=armv4t
-mthumb-interwork -marm -o arm.o -c arm.c
$ arm-cortex_a9-linux-gnueabi-gcc -mcpu=arm7tdmi -march=armv4t
-mthumb-interwork -o thumbtest main.o arm.o
But because I wasn't supplying arm armv4t sysroot it pulled in armv7 crt*.o
files so it showed the same problem as my u-boot.
I think this is resolved now, I modified my simple test to use an armv4t
sysroot and libgcc and verified it does the correct thing, so I'm confident I
can make my u-boot work too. Thanks for your assistance.
-Allen
nvpublic
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