From: Ard Biesheuvel <ardb@kernel.org>
To: Jing Xiangfeng <jingxiangfeng@huawei.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
Darren Hart <dvhart@infradead.org>,
Andy Shevchenko <andy@infradead.org>,
linux-efi <linux-efi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
platform-driver-x86@vger.kernel.org,
Linux-MM <linux-mm@kvack.org>,
Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: Re: [PATCH 0/2] arm64: Support to find mirrored memory ranges
Date: Thu, 20 Feb 2020 10:21:29 +0100 [thread overview]
Message-ID: <CAKv+Gu930691BaDLuoVOU_gz0V8MtfWbfSTKcYuHxDvLz5hAiA@mail.gmail.com> (raw)
In-Reply-To: <1582289580-24045-1-git-send-email-jingxiangfeng@huawei.com>
On Thu, 20 Feb 2020 at 04:43, Jing Xiangfeng <jingxiangfeng@huawei.com> wrote:
>
> This series enable finding mirrored memory ranges
> functionality on arm64 platform. This feature has been
> implemented on the x86 platform, so we move some
> functions from x86.
>
Hello Jing Xiangfeng,
Could you explain your use case a bit better? Usually, the firmware is
a better place to make modifications to the EFI memory map.
The reason I am asking is that currently, on ARM and arm64, we never
make *any* changes to the firmware provided tables (EFI system table,
EFI memory map, DT/ACPI/SMBIOS tables etc), in order to ensure that
kexec is idempotent, i.e., it will always see the exact same state as
far as the firmware is concerned. This is a bit different from x86,
where the memory map is already modified for various other reasons, so
using it for fake memory regions is not such a big deal.
Do you see a use case for this in production?
> Jing Xiangfeng (2):
> efi: allow EFI_FAKE_MEMMAP on arm64 platform
> arm64/efi: support to find mirrored memory ranges
>
> arch/x86/include/asm/efi.h | 5 -----
> arch/x86/platform/efi/efi.c | 39 ---------------------------------------
> drivers/firmware/efi/Kconfig | 2 +-
> drivers/firmware/efi/arm-init.c | 2 ++
> drivers/firmware/efi/efi.c | 23 +++++++++++++++++++++++
> drivers/firmware/efi/memmap.c | 16 ++++++++++++++++
> include/linux/efi.h | 5 +++++
> 7 files changed, 47 insertions(+), 45 deletions(-)
>
> --
> 1.8.3.1
>
next prev parent reply other threads:[~2020-02-20 9:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 12:52 [PATCH 0/2] arm64: Support to find mirrored memory ranges Jing Xiangfeng
2020-02-20 9:21 ` Ard Biesheuvel [this message]
2020-02-21 12:52 ` [PATCH 1/2] efi: allow EFI_FAKE_MEMMAP on arm64 platform Jing Xiangfeng
2020-02-21 12:53 ` [PATCH 2/2] arm64/efi: support to find mirrored memory ranges Jing Xiangfeng
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