From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC PATCH 0/3] efi: MMC proxy support for the UEFI varstore
Date: Thu, 29 Sep 2016 01:54:34 +0200 [thread overview]
Message-ID: <201609290154.34433.arnd@arndb.de> (raw)
In-Reply-To: <1474543806-19210-1-git-send-email-ard.biesheuvel@linaro.org>
On Thursday 22 September 2016, Ard Biesheuvel wrote:
> ================================================================================
> NOTE: this is a work in progress, and not fully functional yet. In particular,
> the actual MMC host protocol methods are stubbed out at the moment, and need to
> be wired up to the Linux device drivers.
> ================================================================================
>
> On mobile and embedded systems, there is usually only a single MMC device for
> non-volatile storage, which sits behind a controller that is owned by the OS at
> runtime. This makes it difficult to host the UEFI variable store on MMC as well,
> since the UEFI runtime services routines expect ownership of the underlying
> device as well.
>
> This series proposes an approach to work around this. It implements the UEFI
> MMC host protocol in the kernel, in a way that makes it possible to expose it
> to the firmware. At the same time, the firmware needs be set up for this, i.e.,
> it needs to expose its MMC host protocol pointer via a UEFI configuration table,
> so that the kernel can override it if it decides to expose this functionality
> to the firmware.
>
> Note that these patches are based on patches in the EFI tree that are queued
> for v4.9, which replace the runtime wrappers spinlock with a semaphore. This
> allows us to sleep in the firmware callbacks.
Would it be possible to implement the UEFI varstore more generally on top
of the Linux pstore interface and then have a pstore backend on top of
MMC? That could give us very similar behavior, but also a bit more flexibility.
It would be a bit confusing to have the 'dmesg' pstore target on top of
UEFI varstore which in turn is on top of pstore on MMC, but I think that's
ok as long as we prevent recursion.
Arnd
next prev parent reply other threads:[~2016-09-28 23:54 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-22 11:30 [RFC PATCH 0/3] efi: MMC proxy support for the UEFI varstore Ard Biesheuvel
2016-09-22 11:30 ` [RFC PATCH 1/3] efi/arm64: add SIMD stash/unstash operations Ard Biesheuvel
2016-09-22 11:30 ` [RFC PATCH 2/3] efi/arm: " Ard Biesheuvel
2016-09-22 11:30 ` [RFC PATCH 3/3] efi: implement MMC proxy support for the UEFI variable store Ard Biesheuvel
2016-09-22 12:58 ` [RFC PATCH 0/3] efi: MMC proxy support for the UEFI varstore Mark Rutland
2016-09-22 13:37 ` Ard Biesheuvel
2016-09-23 9:19 ` Mark Rutland
2016-09-26 15:53 ` Mark Rutland
2016-09-28 23:54 ` Arnd Bergmann [this message]
2016-09-29 0:13 ` Ard Biesheuvel
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