Hi Leif,
On 11/18/2013 12:26 PM, Leif Lindholm wrote:
Commit fe1378a - "ARM: use r9 for gd" - broke the ABI for users of the
U-Boot API on ARM. Users I am aware of are GRUB and the FreeBSD loader.
Since I only spotted this on Saturday, this code is well and truly in
the wild, so any users of the API will need to preserve both r8 and r9
on syscalls for the foreseeable future (which is not the end of the
world).
I actually broke it a bit more than that, since the stubs appear
to use the gd register directly (where I wasn't aware of and
still surprises me a bit, I will have a better look later why this is).
The patch below should help for the hello_world example on master.
(as in both u-boot and the application use r9 for gd)
I am aware this doesn't answer your question and I will come
back on that if I have a bit more time to look into it (Saterday
I guess).
Regards,
Jeroen
diff --git a/examples/standalone/stubs.c b/examples/standalone/stubs.c
index 8fb1765..5d2ab56 100644
--- a/examples/standalone/stubs.c
+++ b/examples/standalone/stubs.c
@@ -40,14 +40,14 @@ gd_t *global_data;
: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) :
"r11");
#elif defined(CONFIG_ARM)
/*
- * r8 holds the pointer to the global_data, ip is a call-clobbered
+ * r9 holds the pointer to the global_data, ip is a call-clobbered
* register
*/
#define EXPORT_FUNC(x) \
asm volatile ( \
" .globl " #x "\n" \
#x ":\n" \
-" ldr ip, [r8, %0]\n" \
+" ldr ip, [r9, %0]\n" \
" ldr pc, [ip, %1]\n" \
: : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) :
"ip");
#elif defined(CONFIG_MIPS)
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