Re: [PATCH v1 3/3] arm64: dts: add Hi6220 mailbox node

From: Leif Lindholm
Date: Tue Aug 25 2015 - 10:24:30 EST


On Tue, Aug 25, 2015 at 09:43:14PM +0800, Haojian Zhuang wrote:
> Since we discussed a lot on this, let's make a conclusion on it.
>
> 1. UEFI could append the reserved buffer in it's memory mapping.

Yes. It needs to.

(I will let Mark comment on points 2-4.)

> 5. A patch is necessary in kernel. If efi stub feature is enabled,
> arm kernel should not parse memory node or reserved memory buffer in
> DT any more.

This is already the case. The stub deletes any present memory nodes and
reserved entries in drivers/firmware/efi/libstub/fdt.c:update_fdt().

Then, during setup_arch(), arch/arm64/kernel/efi.c:efi_init() calls
reserve_regions(), which adds only those memory regions available for
use by Linux as RAM to memblock.

> Arm kernel should either fetch memory information from
> efi or DT.

Absolutely.

> Currently arm kernel fetch both efi memory information and
> reserved buffer from DTB at the same time.

No, it does not.

Regards,

Leif
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