[U-Boot] [PATCH 05/17] x86: Simplify Flash-to-RAM code execution transition
Simon Glass
sjg at chromium.org
Wed Jan 4 06:28:54 CET 2012
Hi Graeme,
On Sun, Jan 1, 2012 at 8:09 PM, Graeme Russ <graeme.russ at gmail.com> wrote:
>
> Signed-off-by: Graeme Russ <graeme.russ at gmail.com>
Commit message?
> ---
> arch/x86/cpu/start.S | 20 +++++---------------
> arch/x86/include/asm/u-boot-x86.h | 2 ++
> arch/x86/lib/board.c | 25 ++++++++++++++++++++++---
> 3 files changed, 29 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S
> index 7f9b6a7..9592158 100644
> --- a/arch/x86/cpu/start.S
> +++ b/arch/x86/cpu/start.S
> @@ -96,32 +96,22 @@ car_init_ret:
> movw $0x85, %ax
> jmp die
>
> -.globl relocate_code
> -.type relocate_code, @function
> -relocate_code:
> +.globl board_init_f_r_trampoline
> +.type board_init_f_r_trampoline, @function
> +board_init_f_r_trampoline:
> /*
> * SDRAM has been initialised, U-Boot code has been copied into
> * RAM, BSS has been cleared and relocation adjustments have been
> * made. It is now time to jump into the in-RAM copy of U-Boot
> *
> * %eax = Address of top of stack
*new* top of stack?
> - * %edx = Address of Global Data
> - * %ecx = Base address of in-RAM copy of U-Boot
> */
>
> /* Setup stack in RAM */
> movl %eax, %esp
>
> - /* Setup call address of in-RAM copy of board_init_r() */
> - movl $board_init_r, %ebp
> - addl (GENERATED_GD_RELOC_OFF)(%edx), %ebp
> -
> - /* Setup parameters to board_init_r() */
> - movl %edx, %eax
> - movl %ecx, %edx
> -
> - /* Jump to in-RAM copy of board_init_r() */
> - call *%ebp
> + /* Re-enter U-Boot by calling board_init_f_r */
> + call board_init_f_r
Isn't this a bit of a funny name? Why not call it something like
call_board_init_r() ?
>
> die:
> hlt
> diff --git a/arch/x86/include/asm/u-boot-x86.h b/arch/x86/include/asm/u-boot-x86.h
> index 755f88a..c3d2277 100644
> --- a/arch/x86/include/asm/u-boot-x86.h
> +++ b/arch/x86/include/asm/u-boot-x86.h
> @@ -61,5 +61,7 @@ u32 isa_map_rom(u32 bus_addr, int size);
> int video_bios_init(void);
> int video_init(void);
>
> +void board_init_f_r_trampoline(ulong) __attribute__ ((noreturn));
> +void board_init_f_r(void) __attribute__ ((noreturn));
>
> #endif /* _U_BOOT_I386_H_ */
> diff --git a/arch/x86/lib/board.c b/arch/x86/lib/board.c
> index ba6b59f..978beaa 100644
> --- a/arch/x86/lib/board.c
> +++ b/arch/x86/lib/board.c
> @@ -253,10 +253,29 @@ void board_init_f(ulong boot_flags)
>
> gd->flags |= GD_FLG_RELOC;
>
> - /* Enter the relocated U-Boot! */
> - relocate_code(gd->start_addr_sp, gd, gd->relocaddr);
> + /*
> + * SDRAM is now initialised, U-Boot has been copied into SDRAM,
> + * the BSS has been cleared etc. The final stack can now be setup
> + * in SDRAM. Code execution will continue (momentarily) in Flash,
> + * but with the stack in SDRAM and Global Data in temporary memory
> + * (CPU cache)
> + */
> + board_init_f_r_trampoline(gd->start_addr_sp);
> +
> + /* NOTREACHED - board_init_f_r_trampoline() does not return */
> + while (1)
> + ;
> +}
> +
> +void board_init_f_r(void)
> +{
> + /*
> + * Transfer execution from Flash to RAM by calculating the address
> + * of the in-RAM copy of board_init_r() and calling it
> + */
> + (board_init_r + gd->reloc_off)(gd, gd->relocaddr);
Nice that this is in C.
Regards,
Simon
>
> - /* NOTREACHED - relocate_code() does not return */
> + /* NOTREACHED - board_init_r() does not return */
> while (1)
> ;
> }
> --
> 1.7.5.2.317.g391b14
>
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