linux-kernel - Re: [PATCH v2] efi/arm64: fix fdt-related memory reservation

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Date:	Mon, 8 Sep 2014 20:58:09 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Mark Salter <msalter@...hat.com>
Cc:	Leif Lindholm <leif.lindholm@...aro.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	matt.fleming@...el.com, Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	linux-arm-kernel@...ts.infradead.org, linux-efi@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] efi/arm64: fix fdt-related memory reservation

On Mon, 08 Sep, at 01:01:08PM, Mark Salter wrote:
> Commit 86c8b27a01cf:
>  "arm64: ignore DT memreserve entries when booting in UEFI mode
> 
> prevents early_init_fdt_scan_reserved_mem() from being called for
> arm64 kernels booting via UEFI. This was done because the kernel
> will use the UEFI memory map to determine reserved memory regions.
> That approach has problems in that early_init_fdt_scan_reserved_mem()
> also reserves the FDT itself and any node-specific reserved memory.
> By chance of some kernel configs, the FDT may be overwritten before
> it can be unflattened and the kernel will fail to boot. More subtle
> problems will result if the FDT has node specific reserved memory
> which is not really reserved.
> 
> This patch has the UEFI stub remove the memory reserve map entries
> from the FDT as it does with the memory nodes. This allows
> early_init_fdt_scan_reserved_mem() to be called unconditionally
> so that the other needed reservations are made.
> 
> Change from v1:
>   * Acks added
>   * Fixed loop logic to remove reserved regions
> 
> Signed-off-by: Mark Salter <msalter@...hat.com>
> Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Acked-by: Mark Rutland <mark.rutland@....com>
> ---
>  arch/arm64/mm/init.c               |  3 +--
>  drivers/firmware/efi/libstub/fdt.c | 10 +++++++++-
>  2 files changed, 10 insertions(+), 3 deletions(-)

Thanks Mark, queued up in 'urgent'.

-- 
Matt Fleming, Intel Open Source Technology Center
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