[PATCH] efi_loader: Allow also empty capsule to be process

Michal Simek michal.simek at amd.com
Thu Jul 20 11:26:14 CEST 2023

On 7/20/23 10:45, Sughosh Ganu wrote:
> On Thu, 20 Jul 2023 at 13:26, Michal Simek <michal.simek at amd.com> wrote:
>> On 7/20/23 08:36, Sughosh Ganu wrote:
>>> On Thu, 20 Jul 2023 at 11:37, Michal Simek <michal.simek at amd.com> wrote:
>>>> Hi,
>>>> On 7/20/23 07:49, AKASHI Takahiro wrote:
>>>>> Hi,
>>>>> On Wed, Jul 19, 2023 at 08:28:41AM +0200, Michal Simek wrote:
>>>>>> On 7/18/23 17:41, Heinrich Schuchardt wrote:
>>>>>>> On 13.07.23 16:35, Michal Simek wrote:
>>>>>>>> Empty capsule are also allowed to be process. Without it updated images
>>>>>>>> can't change their Image Acceptance state from no to yes.
>>>>>>> Is there any documentation describing the usage of empty capsule to set
>>>>>>> the image acceptance state?
>>>>>> I actually don't know about documentation. I was talking to Ilias to make
>>>>>> sure that documentation is up2date because there are missing couple of
>>>>>> things there.
>>>>> Sughosh should have more to say here about A/B update.
>>>>>> I am testing A/B update and if you setup oemflags to 0x8000 then capsules
>>>>>> are not automatically accepted and waiting for acceptance capsule to be
>>>>>> passed.
>>>>>> When I tested it I found out that they are not process that's why I created
>>>>>> this patch.
>>>>> The path you tried to modify is only executed by "efidebug capsule update"
>>>>> or more specifically via the runtime service, UPDATE_CAPSULE.
>>>>> But this API is NOT officially supported in the current capsule implementation
>>>>> (at least, in my initial intention).
>>>>> The only way to invoke capsule updates is to reboot the system.
>>>>> If you want to test A/B update, please do the reboot.
>>>> I realized that to get full flow you need to use capsule update on disk to get
>>>> all functionalities. But it is very impractical. Actually I would expect via
>>>> efidebug you should be able to perform all steps as capsule update performs when
>>>> you do reboot.
>>>> I would also understand that via efidebug you are not able to apply any capsule
>>>> but I don't think it is right that you can apply just update capsules but not
>>>> empty capsules. I would understand none or all but not something in the middle.
>>> The A/B update functionality requires using the capsule-on-disk
>>> functionality for performing the updates. This is also mentioned in
>>> the fwu_updates.rst document. You should be able to apply empty
>>> capsules even with the 'efidebug disk-update' command.
>> Yes this is working fine.
>> ZynqMP> efidebug capsule disk-update
>> #####
>> Applying capsule capsule1.bin succeeded.
>> #########################
>> Applying capsule capsule2.bin succeeded.
>> Reboot after firmware update.
>> I tested it also with empty capsules which are also process properly.
>>> I have never
>>> used the 'efidebug capsule update' command, so I'm not sure if that is
>>> supported. Like Takahiro mentioned, if you place the capsules(genuine
>>> or empty) under the /EFI/UpdateCapsule/ directory, the update should
>>> happen automatically, since the fwu update feature also enables the
>> Yes that's work fine on production systems.
>> But from my point of view there shouldn't be really a problem to also apply
>> empty capsule via efidebug capsule update to be able to see that steps and
>> changes in mdata structure without performing reset.
> The 'efidebug capsule update' command calls the efi_update_capsule
> function, which implements the UpdateCapsule runtime service call. The
> initial versions of my fwu patches were indeed adding support for this
> path, but one of the review comments was to restrict support only for
> the capsule-on-disk path when performing the update in u-boot, since
> we are not using the runtime call in u-boot.

I don't think this is a valid argument. As I said I would understand if there is 
no interface for any capsule. It means having support for both or none is IMHO 
the way we should support.
Can you please point me to that discussion?


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