From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Masayoshi Mizuma <msys.mizuma@gmail.com>,
James Morse <james.morse@arm.com>
Cc: linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-efi <linux-efi@vger.kernel.org>,
Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Kexec Mailing List <kexec@lists.infradead.org>,
d.hatayama@fujitsu.com, Eric Biederman <ebiederm@xmission.com>,
Matthias Brugger <matthias.bgg@gmail.com>
Subject: Re: [PATCH v2 0/2] efi: arm64: Introduce /proc/efi/memreserve to tell the persistent pages
Date: Wed, 4 Dec 2019 09:51:13 +0000 [thread overview]
Message-ID: <CAKv+Gu-teb+3a29cZVc0cxZrXonQeO-EtPugPaQ1QFbeBYjGTw@mail.gmail.com> (raw)
In-Reply-To: <20191203201410.28045-1-msys.mizuma@gmail.com>
On Tue, 3 Dec 2019 at 20:14, Masayoshi Mizuma <msys.mizuma@gmail.com> wrote:
>
> From: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
>
> kexec reboot sometime fails in early boot sequence on aarch64 machine.
> That is because kexec overwrites the LPI property tables and pending
> tables with the initrd.
>
> To avoid the overwrite, introduce /proc/efi/memreserve to tell the
> tables region to kexec so that kexec can avoid the memory region to
> locate initrd.
>
> kexec also needs a patch to handle /proc/efi/memreserve. I'm preparing
> the patch for kexec.
>
> Changelog
> v2: - Change memreserve file location from sysfs to procfs.
> memreserve may exceed the PAGE_SIZE in case efi_memreserve_root
> has a lot of entries. So we cannot use sysfs_kf_seq_show().
> Use seq_printf() in procfs instead.
>
> Masayoshi Mizuma (2):
> efi: add /proc/efi directory
> efi: arm64: Introduce /proc/efi/memreserve to tell the persistent
> pages
>
Apologies for the tardy response.
Adding /proc/efi is really out of the question. *If* we add any
special files to expose this information, it should be under sysfs.
However, this is still only a partial solution, since it only solves
the problem for userspace based kexec, and we need something for
kexec_file_load() as well.
The fundamental issue here is that /proc/iomem apparently lacks the
entries that describe these regions as 'reserved', so we should try to
address that instead.
prev parent reply other threads:[~2019-12-04 9:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-03 20:14 [PATCH v2 0/2] efi: arm64: Introduce /proc/efi/memreserve to tell the persistent pages Masayoshi Mizuma
2019-12-03 20:14 ` [PATCH v2 1/2] efi: add /proc/efi directory Masayoshi Mizuma
2019-12-03 20:14 ` [PATCH v2 2/2] efi: arm64: Introduce /proc/efi/memreserve to tell the persistent pages Masayoshi Mizuma
2019-12-04 8:50 ` d.hatayama
2019-12-04 9:51 ` Ard Biesheuvel [this message]
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