[U-Boot] [PATCH] arm: spl: Allow board_init_r() to run with a larger stack
Simon Glass
sjg at chromium.org
Mon Jan 19 20:38:06 CET 2015
Hi,
On 18 January 2015 at 23:46, Heiko Schocher <hs at denx.de> wrote:
> Hello Simon,
>
> added Bo Shen to cc, as he currently try to set BSS (and stack) into
> SDRAM for at91 based boards ... Bo, could you try this aproach?
>
> Am 18.01.2015 19:55, schrieb Simon Glass:
>
>> 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 now:
>>
>> Execution starts with start.S. Two main functions can be provided by the
>> board implementation. The purpose and limitations of each is described
>> below.
>> After that, the common board_init_r() is called to perform the SPL task.
>>
>> lowlevel_init():
>> - purpose: essential init to permit execution to reach
>> board_init_f()
>> - no global_data, but there is a stack
>> - must not set up SDRAM or use console
>> - must only do the bare minimum to allow execution to continue to
>> board_init_f()
>> - this is almost never needed
>> - return normally from this function
>>
>> board_init_f():
>> - purpose: set up the machine ready for running board_init_r():
>> i.e. SDRAM and serial UART
>> - global_data is available
>> - preloader_console_init() can be called here in extremis
>> - stack is in SRAM
>> - should set up SDRAM, and anything needed to make the UART work
>> - these is no need to clear BSS, it will be done by crt0.S
>> - must return normally from this function (don't call
>> board_init_r()
>> directly)
>>
>> Here the BSS is cleared. If CONFIG_SPL_STACK_R is defined, then at this
>> point
>> the stack and global_data are relocated to below that address.
>>
>> board_init_r():
>> - purpose: main execution, common code
>> - global_data is available
>> - SDRAM is available
>> - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined
>> and
>> points into SDRAM
>> - preloader_console_init() can be called here - typically this is
>> done by defining CONFIG_SPL_BOARD_INIT and then supplying
>> a
>> spl_board_init() function containing this call
>> - loads U-Boot or (in falcon mode) Linux
>>
>> Note: This patch is intended to apply over the top of Tom's SPL changes
>> and
>
>
> Sound good! Can you point me, which patches you mean? Thanks!
>
Tom's ones are here, although he is planning to update them I think.
http://patchwork.ozlabs.org/patch/422992/
http://patchwork.ozlabs.org/patch/422993/
>> this series:
>>
>> https://patchwork.ozlabs.org/patch/423785/
>>
>> Signed-off-by: Simon Glass <sjg at chromium.org>
>> ---
>>
>> arch/arm/lib/crt0.S | 13 ++++++++++---
>> common/spl/spl.c | 35 +++++++++++++++++++++++++++++++++++
>> doc/README.SPL | 42 ++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 87 insertions(+), 3 deletions(-)
>
>
> Hmm... I miss here "arch/arm/lib/spl.c" where "clearing BSS"
> should get removed ... or?
>
I haven't removed it from existing board code, just added it to crt0.S
so that it will then be possible to clean up the board code.
>
>> 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 1826c47..78bb279 100644
>> --- a/common/spl/spl.c
>> +++ b/common/spl/spl.c
>> @@ -276,3 +276,38 @@ 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
>> +}
>
>
> I try this patch out on a sam9260 board with 4k sram for SPL (if I have the
> hw) ... looking into my current objdump with the approach from Bo,
> see patch [1], I do not find "memcpy" in it ... I currently have a
> SPL size (untested, compiled code only) currently from 3392 bytes, which
> perfectly fits in 4k ... adding a memcpy in code, I get a size of 3464 bytes
> fits also in 4k ... with space for some init stack in sram ... so, I try
> your patch ASAP, thanks!
OK thanks.
- Simon
More information about the U-Boot
mailing list