[RFC 00/14] efi_loader: add capsule update support

Sughosh Ganu sughosh.ganu at linaro.org
Wed Mar 18 19:16:43 CET 2020

On Tue, 17 Mar 2020 at 07:42, AKASHI Takahiro <takahiro.akashi at linaro.org>

> Summary
> =======
> 'UpdateCapsule' is one of runtime services defined in UEFI specification
> and its aim is to allow a caller to pass information to the firmware.
> This is mostly used to update firmware binary on devices by instructions
> from OS.
> In this patch series, all the related definitions and structures are given
> as UEFI specification describes and basic framework for capsule support is
> implemented. Currently supported types of capsule are
>  * firmware update (Firmware Management Protocol or simply FMP)
>  * variable update
> UpdateCapsule is a runtime services function, but is, at least initially,
> provided only before exiting boot services alike other runtime functions.
> This is because modifying storage which may be shared with OS must be
> carefully designed and there is no general assumption to do that as in
> the case of [Get/]SetVariable.
> Instead, any capsule can be handed over to the firmware as a file on
> a specific file system. In other words, we only support "capsules on disk"
> for now.
> Regarding firmware update, most of functionality is provided by FMP
> driver and it will be by nature system/platform-specific. So you can and
> should implement FMP drivers based on your system requirements.
> In this patch series, only a simple FMP driver based on FIT image for
> a single region is supported.  (So it is "for reference only")
> See more details in "efi_loader: capsule: add simple firmware management
> protocol."
> Regarding variable update, the implementation here is based on a draft
> proposal[1] by Peter in Boot-arch ML. The specification should be discussed
> and finalized first. So the code doesn't fully implement Peter's idea.
> [1]
> https://lists.linaro.org/pipermail/boot-architecture/2018-October/000883.html
> Patch structure
> ===============
> Patch#1-#4: preparatory patches
> Patch#5-#11: main part of implementation
> Patch#12-#14: utilities and tests
With the changes that I suggested in a couple of patches, I am able to test
the capsule-on-disk update of the u-boot firmware image on the qemu arm64
platform. I have also tested the capsule update functionality via the
'efidebug capsule update -v <capsule address>' command. Thanks!


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