On Tue, Mar 03, 2015 at 08:03:00AM -0700, Simon Glass wrote:
> At present SPL uses a single stack, either CONFIG_SPL_STACK or
> CONFIG_SYS_INIT_SP_ADDR. Since some SPL features (such as MMC and
> environment) require a lot of stack, some boards set CONFIG_SPL_STACK to
> point into SDRAM. They then set up SDRAM very early, before board_init_f(),
> so that the larger stack can be used.
>
> This is an abuse of lowlevel_init(). That function should only be used for
> essential start-up code which cannot be delayed. An example of a valid use is
> when only part of the SPL code is visible/executable, and the SoC must be set
> up so that board_init_f() can be reached. It should not be used for SDRAM
> init, console init, etc.
>
> Add a CONFIG_SPL_STACK_R option, which allows the stack to be moved to a new
> address before board_init_r() is called in SPL.
>
> The expected SPL flow (for CONFIG_SPL_FRAMEWORK) is documented in the README.
>
> Signed-off-by: Simon Glass <s...@chromium.org>
> For version 1:
> Acked-by: Albert ARIBAUD <albert.u.b...@aribaud.net>
> Reviewed-by: Stefan Roese <s...@denx.de>
> Tested-by: Bo Shen <voice.s...@atmel.com>
> Acked-by: Bo Shen <voice.s...@atmel.com>
> Acked-by: Heiko Schocher <h...@denx.de>
> Tested-by: Heiko Schocher <h...@denx.de>
> ---
>
> Changes in v6: None
> Changes in v5:
> - Rebase to master
>
> Changes in v4:
> - Adjust README to mention that lowlevel_init() should have no stack
>
> Changes in v3: None
> Changes in v2:
> - Move docs to top-level README file and expand them to cover U-Boot proper
> - Add Kconfig settings
>
> Kconfig | 18 ++++++++++++++
> README | 69
> +++++++++++++++++++++++++++++++++++++++++++++++++++++
> arch/arm/lib/crt0.S | 13 +++++++---
> common/spl/spl.c | 35 +++++++++++++++++++++++++++
> 4 files changed, 132 insertions(+), 3 deletions(-)
[snip]
> diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
> index 22df3e5..7939ced 100644
> --- a/arch/arm/lib/crt0.S
> +++ b/arch/arm/lib/crt0.S
> @@ -113,7 +113,14 @@ here:
> /* Set up final (full) environment */
>
> bl c_runtime_cpu_setup /* we still call old routine here */
> -
> +#endif
> +#if !defined(CONFIG_SPL_BUILD) || defined(CONFIG_SPL_FRAMEWORK)
> +# ifdef CONFIG_SPL_BUILD
> + /* Use a DRAM stack for the rest of SPL, if requested */
> + bl spl_relocate_stack_gd
> + cmp r0, #0
> + movne sp, r0
> +# endif
> ldr r0, =__bss_start /* this is auto-relocated! */
> ldr r1, =__bss_end /* this is auto-relocated! */
>
> @@ -124,9 +131,10 @@ clbss_l:cmp r0, r1 /* while not at
> end of BSS */
> addlo r0, r0, #4 /* move to next */
> blo clbss_l
>
> +#if ! defined(CONFIG_SPL_BUILD)
> bl coloured_LED_init
> bl red_led_on
> -
> +#endif
> /* call board_init_r(gd_t *id, ulong dest_addr) */
> mov r0, r9 /* gd_t */
> ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */
> @@ -134,7 +142,6 @@ clbss_l:cmp r0, r1 /* while not at
> end of BSS */
> ldr pc, =board_init_r /* this is auto-relocated! */
>
> /* we should not return here. */
> -
> #endif
>
> ENDPROC(_main)
> diff --git a/common/spl/spl.c b/common/spl/spl.c
> index ded0f30..cd75bbc 100644
> --- a/common/spl/spl.c
> +++ b/common/spl/spl.c
> @@ -281,3 +281,38 @@ void preloader_console_init(void)
> spl_display_print();
> #endif
> }
> +
> +/**
> + * spl_relocate_stack_gd() - Relocate stack ready for board_init_r()
> execution
> + *
> + * Sometimes board_init_f() runs with a stack in SRAM but we want to use
> SDRAM
> + * for the main board_init_r() execution. This is typically because we need
> + * more stack space for things like the MMC sub-system.
> + *
> + * This function calculates the stack position, copies the global_data into
> + * place and returns the new stack position. The caller is responsible for
> + * setting up the sp register.
> + *
> + * @return new stack location, or 0 to use the same stack
> + */
> +ulong spl_relocate_stack_gd(void)
> +{
> +#ifdef CONFIG_SPL_STACK_R
> + gd_t *new_gd;
> + ulong ptr;
> +
> + /* Get stack position: use 8-byte alignment for ABI compliance */
> + ptr = CONFIG_SPL_STACK_R - sizeof(gd_t);
> + ptr &= ~7;
> + new_gd = (gd_t *)ptr;
> + memcpy(new_gd, (void *)gd, sizeof(gd_t));
> + gd = new_gd;
> +
> + /* Clear the BSS. */
> + memset(__bss_start, 0, __bss_end - __bss_start);
> +
> + return ptr;
> +#else
> + return 0;
> +#endif
> +}All of this _does_ move gd into where CONFIG_SPL_STACK_R points. It does _not_ move the stack itself into where CONFIG_SPL_STACK_R points so the big use case (am335x_boneblack for example where CONFIG_SPL_ENV_SUPPORT is set) doesn't work and blows up as we overflow the area for stack. -- Tom
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