Re: [PATCH] arm64: dts: renesas: r8a78000: Describe all reserved memory

[Geert Uytterhoeven]

Hi Marek,

s/r8a78000/ironhide/ in the one-line summary

On Sun, 17 May 2026 at 18:32, Marek Vasut
<marek.vasut+renesas@xxxxxxxxxxx> wrote:
> Fully describe all available DRAM in the DT, and describe regions which
> are not accessible because they are used by firmware in reserved-memory
> node.
>
> Replace first memory bank memory@60600000 with memory@40000000 and a
> 518 MiB long reserved-memory no-map subnode. This memory region is used
> by other cores in the system.
>
> Reserve 32 kiB of memory at 0x8c100000 for parameters shared by IPL,
> SCP, TFA BL31 and TEE.
>
> Reserve 512 kiB of memory at 0x8c200000 for TFA BL31. The upcoming
> upstream TFA 2.15 BL31 uses memory from 0x8c200000..0x8c242fff, the
> round up to 512 kiB is slight future proofing.
>
> Reserve 32 MiB of memory at 0x8c400000 for OPTEE-OS, which is the
> entire OPTEE-OS TZ protected DRAM area.
>
> Neither the TFA BL31 nor OPTEE-OS do modify the DT passed to Linux in
> any way with any new reserved-memory {} node to reserve memory areas
> used by the TFA BL31 or OPTEE-OS to prevent the next stage from using
> those areas, which lets Linux use all of the available DRAM as it is
> described in the DT that was passed in by U-Boot, including the areas
> that are newly utilized by TFA BL31 or OPTEE-OS.

Thanks for your patch!

> In case of high DRAM utilization, unless the memory used by TFA BL31
> or OPTEE-OS is properly reserved, Linux may use and corrupt the memory
> used by TFA BL31 or OPTEE-OS, which would lead to the system becoming
> unresponsive.

Oh well...

> Fixes: ad142a4ef710 ("arm64: dts: renesas: r8a78000: Add initial Ironhide board support")
> Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>

LGTM, so
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
i.e. will queue in renesas-devel for v7.2.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds