Hi Heinrich,
On Sun, 3 Nov 2024 at 10:23, Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 11/3/24 01:28, Simon Glass wrote:
The reserve_stack_aligned() function already ensures that the resulting address is aligned to a 16-byte boundary. The comment seems to suggest that 16 is passed reserve_stack_aligned() to make it aligned.
Change the value to 0, since the stack can start at the current address, if it is suitably aligned already.
Signed-off-by: Simon Glass sjg@chromium.org
(no changes since v1)
common/board_f.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/common/board_f.c b/common/board_f.c index 98dc2591e1d..677e37d93c0 100644 --- a/common/board_f.c +++ b/common/board_f.c @@ -601,7 +601,7 @@ __weak int arch_reserve_stacks(void) static int reserve_stacks(void) { /* make stack pointer 16-byte aligned */
gd->start_addr_sp = reserve_stack_aligned(16);
gd->start_addr_sp = reserve_stack_aligned(0);In 1938f4a5b62f ("Introduce generic pre-relocation board_f.c") you wrote:
/* setup stack pointer for exceptions */ gd->dest_addr_sp -= 16; /* leave 3 words for abort-stack, plus 1 for alignment */ gd->dest_addr_sp -= 16;
Is that not relevant anymore?
Well that looks like ARM code that has moved to arch_reserve_stacks() some time ago.
Does all and every U-Boot architecture decrement the stack pointer before writing values to the stack?
E.g. Microblaze, MIPS, RISC-V, and Super-H do not have a dedicated PUSH instruction.
I'm not sure about that, but they certainly need to. I see that powerpc seems to write to values above the stack top! I don't think we have enough people on this patch to look into powerpc, at least.
For RISC-V, does it use a full-descending stack, or empty? Looking at relocate_code() I don't see it subtracting anything from the stack-pointer that is passed in.
Regards, SImon