Re: [PATCH v2 02/10] spl: atf: support Linux as BL33 with TFA

Tom Rini <[email protected]> Fri, 31 Jul 2026 12:47:30 -0600
Newsgroups	gmane.comp.boot-loaders.u-boot
Message-ID	<20260731184730.GO1773261@bill-the-cat>
On Fri, Jul 31, 2026 at 09:10:46PM +0400, Alexey Charkov wrote:
> Modern SoCs such as Rockchip RK3576 need TFA to be running to provide
> firmware services to the OS.
> 
> Enable the TFA boot flow to allow using Linux as BL33 (including its
> calling convention) to facilitate Falcon mode boot on such SoCs.
> 
> Signed-off-by: Alexey Charkov <[email protected]>
> ---
>  common/spl/Kconfig   | 22 ++++++++++++++++++++--
>  common/spl/spl_atf.c | 49 +++++++++++++++++++++++++++++++++----------------
>  2 files changed, 53 insertions(+), 18 deletions(-)
> 
> diff --git a/common/spl/Kconfig b/common/spl/Kconfig
> index 0618f42c9410..7c639ed8f763 100644
> --- a/common/spl/Kconfig
> +++ b/common/spl/Kconfig
> @@ -1230,22 +1230,40 @@ config SPL_BOOTZ
>  	help
>  	  Boot a linux zimage from memory in falcon boot.
>  
> +	  This provides an entry path which is unused when the OS is entered
> +	  through TF-A, since SPL then only places the kernel in memory and
> +	  BL31 is what enters it. It remains selectable: SPL can still enter
> +	  a kernel itself on such a platform, dropping to EL2 without TF-A
> +	  resident, just without any firmware services being available to the
> +	  OS afterwards.
> +
>  config SPL_BOOTI
>  	bool "Allow booting an Image style Linux kernel from SPL"
>  	depends on SPL_OS_BOOT && !SPL_OS_BOOT_SECURE
> -	default y if ARM64 || RISCV
> +	default y if (ARM64 || RISCV) && !SPL_ATF
>  	select SPL_LIB_BOOTI
>  	help
>  	  Boot an uncompressed linux kernel image from memory in falcon boot.
>  
> +	  This provides an entry path which is unused when the OS is entered
> +	  through TF-A, since SPL then only places the kernel in memory and
> +	  BL31 is what enters it, so it does not default to y in that case. It
> +	  remains selectable: SPL can still enter a kernel itself on such a
> +	  platform, dropping to EL2 without TF-A resident, just without any
> +	  firmware services being available to the OS afterwards.
> +
>  config SPL_OS_BOOT_ARGS
>  	bool "Allow SPL to load args for kernel in falcon mode"
>  	depends on (SPL_OS_BOOT || SPL_LOAD_FIT_OPENSBI_OS_BOOT) && !SPL_OS_BOOT_SECURE
> -	default y if !SPL_OS_BOOT_SECURE
> +	default y if !SPL_OS_BOOT_SECURE && !SPL_ATF
>  	help
>  	  This option enables the SPL to load an args file (usually the FDT)
>  	  alongside the kernel image in falcon boot mode.
>  
> +	  This is not needed when the OS is entered through TF-A, since the
> +	  device tree is then taken from the same FIT as the kernel, which is
> +	  why it does not default to y in that case.
> +
>  config SPL_PAYLOAD_ARGS_ADDR
>  	hex "Address in memory to load 'args' file for Falcon Mode to"
>  	depends on SPL_OS_BOOT_ARGS

Expanding on the help text is good. I'm not immediately sure on changing
the default statements however. Maybe the changes are fine but just need
a bit of a rewording to be a tiny bit more concise, the "which is why it
does not default to y in that case" can probably be dropped and you just
add text explaining when it's not appropriate to enable.

-- 
Tom
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