[U-Boot] [PATCH] arm: Correct comments in crt0.S for the recent SPL improvements

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hello Simon,

On Sat,  1 Aug 2015 08:55:46 -0600, Simon Glass <sjg@chromium.org> wrote:
> The current comments need a bit of tweaking since we now support stack
> and global_data relocation in SPL. Also add a reference to the README.
> 
> For AArch64 this is not implemented, so leave a TODO for this.
> 
> Signed-off-by: Simon Glass <sjg@chromium.org>
> Reported-by: Tim Harvey <tharvey@gateworks.com>
> ---
> 
>  arch/arm/lib/crt0.S    | 26 ++++++++++++++++----------
>  arch/arm/lib/crt0_64.S | 30 ++++++++++++++++++++----------
>  2 files changed, 36 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
> index afd4f10..4c3a94a 100644
> --- a/arch/arm/lib/crt0.S
> +++ b/arch/arm/lib/crt0.S
> @@ -25,7 +25,8 @@
>   *    the GD ('global data') structure, both located in some readily
>   *    available RAM (SRAM, locked cache...). In this context, VARIABLE
>   *    global data, initialized or not (BSS), are UNAVAILABLE; only
> - *    CONSTANT initialized data are available.
> + *    CONSTANT initialized data are available. GD should be zeroed
> + *    before board_init_f() is called.
>   *
>   * 2. Call board_init_f(). This function prepares the hardware for
>   *    execution from system RAM (DRAM, DDR...) As system RAM may not
> @@ -34,24 +35,29 @@
>   *    data include the relocation destination, the future stack, and
>   *    the future GD location.
>   *
> - * (the following applies only to non-SPL builds)
> - *
>   * 3. Set up intermediate environment where the stack and GD are the
>   *    ones allocated by board_init_f() in system RAM, but BSS and
>   *    initialized non-const data are still not available.
>   *
> - * 4. Call relocate_code(). This function relocates U-Boot from its
> - *    current location into the relocation destination computed by
> - *    board_init_f().
> + * 4a.For U-Boot proper (not SPL), call relocate_code(). This function
> + *    relocates U-Boot from its current location into the relocation
> + *    destination computed by board_init_f().
> + *
> + * 4b.For SPL, board_init_f() just returns (to crt0). There is no
> + *    code relocation in SPL.
>   *
>   * 5. Set up final environment for calling board_init_r(). This
>   *    environment has BSS (initialized to 0), initialized non-const
>   *    data (initialized to their intended value), and stack in system
> - *    RAM. GD has retained values set by board_init_f(). Some CPUs
> - *    have some work left to do at this point regarding memory, so
> - *    call c_runtime_cpu_setup.
> + *    RAM (for SPL moving the stack and GD into RAM is optional - see
> + *    CONFIG_SPL_STACK_R). GD has retained values set by board_init_f().
> + *
> + * 6. For U-Boot proper (not SPL), some CPUs have some work left to do
> + *    at this point regarding memory, so call c_runtime_cpu_setup.
> + *
> + * 7. Branch to board_init_r().
>   *
> - * 6. Branch to board_init_r().
> + * For more information see 'Board Initialisation Flow in README.
>   */
>  
>  /*
> diff --git a/arch/arm/lib/crt0_64.S b/arch/arm/lib/crt0_64.S
> index 98a906e..8b34e04 100644
> --- a/arch/arm/lib/crt0_64.S
> +++ b/arch/arm/lib/crt0_64.S
> @@ -27,7 +27,8 @@
>   *    the GD ('global data') structure, both located in some readily
>   *    available RAM (SRAM, locked cache...). In this context, VARIABLE
>   *    global data, initialized or not (BSS), are UNAVAILABLE; only
> - *    CONSTANT initialized data are available.
> + *    CONSTANT initialized data are available. GD should be zeroed
> + *    before board_init_f() is called.
>   *
>   * 2. Call board_init_f(). This function prepares the hardware for
>   *    execution from system RAM (DRAM, DDR...) As system RAM may not
> @@ -36,24 +37,31 @@
>   *    data include the relocation destination, the future stack, and
>   *    the future GD location.
>   *
> - * (the following applies only to non-SPL builds)
> - *
>   * 3. Set up intermediate environment where the stack and GD are the
>   *    ones allocated by board_init_f() in system RAM, but BSS and
>   *    initialized non-const data are still not available.
>   *
> - * 4. Call relocate_code(). This function relocates U-Boot from its
> - *    current location into the relocation destination computed by
> - *    board_init_f().
> + * 4a.For U-Boot proper (not SPL), call relocate_code(). This function
> + *    relocates U-Boot from its current location into the relocation
> + *    destination computed by board_init_f().
> + *
> + * 4b.For SPL, board_init_f() just returns (to crt0). There is no
> + *    code relocation in SPL.
>   *
>   * 5. Set up final environment for calling board_init_r(). This
>   *    environment has BSS (initialized to 0), initialized non-const
>   *    data (initialized to their intended value), and stack in system
> - *    RAM. GD has retained values set by board_init_f(). Some CPUs
> - *    have some work left to do at this point regarding memory, so
> - *    call c_runtime_cpu_setup.
> + *    RAM (for SPL moving the stack and GD into RAM is optional - see
> + *    CONFIG_SPL_STACK_R). GD has retained values set by board_init_f().
> + *
> + * TODO: For SPL, implement stack relocation on AArch64.
>   *
> - * 6. Branch to board_init_r().
> + * 6. For U-Boot proper (not SPL), some CPUs have some work left to do
> + *    at this point regarding memory, so call c_runtime_cpu_setup.
> + *
> + * 7. Branch to board_init_r().
> + *
> + * For more information see 'Board Initialisation Flow in README.
>   */
>  
>  ENTRY(_main)
> @@ -106,6 +114,8 @@ relocation_return:
>   */
>  	bl	c_runtime_cpu_setup		/* still call old routine */
>  
> +/* TODO: For SPL, call spl_relocate_stack_gd() to alloc stack relocation */
> +
>  /*
>   * Clear BSS section
>   */
> -- 
> 2.5.0.rc2.392.g76e840b
> 

Applied to u-boot-arm/master, thanks!

Amicalement,
-- 
Albert.