[U-Boot] [PATCH v6 4/6] arm: spl: Allow board_init_r() to run with a larger stack
Simon Glass
sjg at chromium.org
Wed Mar 4 04:23:23 CET 2015
Hi Tom,
On 3 March 2015 at 13:14, Tom Rini <trini at konsulko.com> wrote:
> On Tue, Mar 03, 2015 at 12:04:16PM -0700, Simon Glass wrote:
>> Hi Tom,
>>
>> On 3 March 2015 at 10:49, Tom Rini <trini at konsulko.com> wrote:
>> > 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 <sjg at chromium.org>
>> >> For version 1:
>> >> Acked-by: Albert ARIBAUD <albert.u.boot at aribaud.net>
>> >> Reviewed-by: Stefan Roese <sr at denx.de>
>> >> Tested-by: Bo Shen <voice.shen at atmel.com>
>> >> Acked-by: Bo Shen <voice.shen at atmel.com>
>> >> Acked-by: Heiko Schocher <hs at denx.de>
>> >> Tested-by: Heiko Schocher <hs at 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.
>>
>> OK I'll have to test more. What sort of problem should i see?
>
> We hang on entering env_reloc_spec() which is what puts some big sized
> variables on the stack.
>
>> The return value from spl_relocate_stack_gd() should be shoved into
>> sp. Does that not happen?
>
> It doesn't appear to be. I hadn't broken out the BBB with JTAG tho.
I printed out the stack in board_init_r() and it looks right: 32MB
above the base of SDRAM.
Also I don't seem to get a crash in SPL. How do I make that happen? If
I define CONFIG_SPL_USBETH_SUPPORT I get an error about the .data
section not fitin in .sram for u-boot-spl.
Regards,
Simon
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