On Tue, Jun 15, 2021 at 12:48 PM Geert Uytterhoeven
[off-list ref] wrote:

Hi Nick,

On Tue, Jun 15, 2021 at 8:29 PM Nick Kossifidis [off-list ref] wrote:

quoted

Στις 2021-06-15 16:19, Geert Uytterhoeven έγραψε:

quoted

This does not match
https://github.com/devicetree-org/dt-schema/blob/master/schemas/chosen.yaml#L77:

    $ref: types.yaml#/definitions/uint64-array
    maxItems: 2
    description:
      This property (currently used only on arm64) holds the memory
range,
      the address and the size, of the elf core header which mainly
describes
      the panicked kernel\'s memory layout as PT_LOAD segments of elf
format.

Hence "linux,elfcorehdr" should be a property of the /chosen node,
instead of a memory node with a compatible value of "linux,elfcorehdr".

That's a binding for a property on the /chosen node, that as the text
says it's defined for arm64 only and the code that handled it was also

That doesn't mean it must not be used on other architectures ;-)
Arm64 was just the first one to use it...

It is used on arm64 because memory is often passed by UEFI tables and
not with /memory node. As riscv is also supporting EFI, I'd think they
would do the same.

quoted

on arm64. Instead the reserved-region binding I used is a standard
binding, if you don't like the name used for the compatible string
because it overlaps with that property we can change it. I want to use a
reserved-region for this because we'll have to reserve it anyway so
using a property on /chosen and then using that property to reserve the
region seemed suboptimal.

quoted

quoted

v2:
 * Use linux,usable-memory on /memory instead of a new binding

This part seems to have been removed in v3 and later?
Note that "linux,usable-memory-range" should be a property of the
/chosen node, too, cfr.
https://github.com/devicetree-org/dt-schema/blob/master/schemas/chosen.yaml#L85

No special handling is needed when using linux,usable-memory on /memory,
limiting the available memory is handled by generic code at
drivers/of/fdt.c

It was my understanding both properties under /chosen are the
recommended methods for new platforms... Let's see what Rob has
to say...

Anyway, I sent a patch series to switch to generic "linux,elfcorehdr"
handling
https://lore.kernel.org/r/cover.1623780059.git.geert+renesas@glider.be/ (local)

Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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

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