Hi, On 11/11/25 3:14 PM, Sascha Hauer wrote: > On Mon, Nov 10, 2025 at 09:34:50PM +0100, Marco Felsch wrote: >> Add support to store a FDT within the scratch area. The user needs to >> query the location and size via imx_scratch_get_fdt() which can be used >> afterwards to write the actual FDT into it. >> >> Signed-off-by: Marco Felsch <[email protected]> >> --- >> arch/arm/mach-imx/scratch.c | 16 ++++++++++++++++ >> common/Kconfig | 14 ++++++++++++++ >> include/mach/imx/scratch.h | 2 ++ >> 3 files changed, 32 insertions(+) >> >> diff --git a/arch/arm/mach-imx/scratch.c b/arch/arm/mach-imx/scratch.c >> index >> e4e2d25969f061c9fcdfd7c3d87701b715eb2805..9c0f1c09c4e0b863d8c95888db7cf0518f698d53 >> 100644 >> --- a/arch/arm/mach-imx/scratch.c >> +++ b/arch/arm/mach-imx/scratch.c >> @@ -16,7 +16,10 @@ struct imx_scratch_space { >> u32 bootrom_log[128]; >> u32 reserved[128]; /* reserve for bootrom log */ >> struct optee_header optee_hdr; >> + /* FDT needs an 8 byte alignment */ >> + u8 fdt[CONFIG_SCRATCH_FDT_SIZE] __aligned(8); >> }; >> +static_assert(sizeof(struct imx_scratch_space) <= CONFIG_SCRATCH_SIZE); >> >> static struct imx_scratch_space *scratch; >> >> @@ -92,3 +95,16 @@ const struct optee_header *imx_scratch_get_optee_hdr(void) >> >> return &scratch->optee_hdr; >> } >> + >> +void imx_scratch_get_fdt(void **fdt, unsigned int *fdt_sz) >> +{ >> + if (!scratch) { >> + if (IN_PBL) >> + return; >> + else >> + scratch = (void *)arm_mem_scratch_get(); >> + } >> + >> + *fdt = scratch->fdt; >> + *fdt_sz = sizeof(scratch->fdt); >> +} >> diff --git a/common/Kconfig b/common/Kconfig >> index >> eb2fb1da1e0919b6e7d5e868c48ad2e195cd8aa8..3f394416c3c376d1cf842472803a47462bb012ed >> 100644 >> --- a/common/Kconfig >> +++ b/common/Kconfig >> @@ -302,8 +302,22 @@ config MALLOC_SIZE >> config SCRATCH_SIZE >> hex >> default 0x8000 >> + default 0x48000 if PBL_EARLY_FDT_LOAD
Easy to misconfigure. How about an additional: range 0x48000 <some big size> if PBL_EARLY_FDT_LOAD >> prompt "Scratch size" > > Do I get this right that the scratch space now includes the space for > the early FDT? If yes then this can lead to inconsistencies when the > scratch space is to small. Why not add an extra space? I would prefer we do not complicate the "endmem" layout more than we have currently. What I think we want in future is an API to allocate from the scratch mem a handoff block and there would be no hardcoded offsets and struct imx_scratch_space could go away. To save handoff when switching from PBL to proper, we would then also allocate to the scratch space. This will probably happen separately, so I am in favor of not creating a new section that's removed afterwards. Cheers, Ahmad > > Sascha > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
