[U-Boot] [PATCH] arm: add 8-byte alignment for ABI compliance before board_init_f

Reinhard Meyer
2010-11-12T07:06:17Z

Dear Heiko Schocher,
> diff --git a/arch/arm/cpu/sa1100/start.S b/arch/arm/cpu/sa1100/start.S
> index ace0c07..91cdd72 100644
> --- a/arch/arm/cpu/sa1100/start.S
> +++ b/arch/arm/cpu/sa1100/start.S
> @@ -152,6 +152,7 @@ reset:
> /* Set stackpointer in internal RAM to call board_init_f */
> call_board_init_f:
> ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
> + bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
> ldr r0,=0x00000000
> bl board_init_f
>
> diff --git a/arch/arm/lib/board.c b/arch/arm/lib/board.c
> index 1fd5f83..96c0e30 100644
> --- a/arch/arm/lib/board.c
> +++ b/arch/arm/lib/board.c
> @@ -276,7 +276,7 @@ void board_init_f (ulong bootflag)
> ulong addr, addr_sp;
>
> /* Pointer is writable since we allocated a register for it */
> - gd = (gd_t *) (CONFIG_SYS_INIT_SP_ADDR);
> + gd = (gd_t *) ((CONFIG_SYS_INIT_SP_ADDR)& ~0x07);
> /* compiler optimization barrier needed for GCC>= 3.4 */
> __asm__ __volatile__("": : :"memory");
>

Is bootflag ever used? If not, why not change the parameter to
give the gd address to board_init_f?

ld r0, sp (whatever the exact assembly syntax for that would be)

void board_init_f (gd_t *gd_addr)
...
gd = gd_addr;

One further thought, why not init the reserved register in assembly and
remove the gd relevant code in C? But that bears some risk if the register
is changed and the assembly is forgotten to adapt..

Best regards,
Reinhard