Re: [PATCH v2] arm64: dts: renesas: ironhide: Describe inline ECC carveouts

[Geert Uytterhoeven]

On Mon, 13 Jul 2026 at 11:11, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> On Fri, 10 Jul 2026 at 18:05, Marek Vasut
> <marek.vasut+renesas@xxxxxxxxxxx> wrote:
> > The DBSC5 DRAM controller protects DRAM content using inline ECC.
> > The inline ECC utilizes areas of DRAM for its operation, which are
> > in the DRAM address range, but must not be accessed or modified.
> > Describe the inline ECC carveout areas used by the DBSC5 controller
> > on this hardware as reserved-memory, which must not be accessed.
> > Include DRAM areas which are unprotected by ECC as well, those are
> > parts of the DRAM which directly precede the ECC carveout.
> >
> > In case of high DRAM utilization, unless the inline ECC carveouts
> > are properly reserved, Linux may use and corrupt the memory used
> > by the DBSC5 DRAM controller for inline ECC, which would lead to
> > the system becoming unstable.
> >
> > Fixes: ad142a4ef710 ("arm64: dts: renesas: r8a78000: Add initial Ironhide board support")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
>
> > V2: Include the unprotected data areas as well
>
> Thanks for the update!
>
> With the ECC carveouts, Ironhide survives booting with "earlycon
> memtest=17".

Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
(also with all offsets set to 0xcccc0000).

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