Re: [PATCH v2] efivarfs: add nostatfs mount option to skip QueryVariableInfo()

[Ard Biesheuvel]

On Thu, 24 Sep 2026, at 13:36, Luis Claudio R. Goncalves wrote:
> On Thu, Sep 24, 2026 at 12:19:23PM +0100, Steve McIntyre wrote:
>> Hey all,
>> 
>> On Thu, Sep 24, 2026 at 08:05:34AM -0300, Luis Claudio R. Goncalves wrote:
>> >On Fri, Sep 18, 2026 at 09:41:24PM -0700, Prashant Singh wrote:
>> >
>> >I tested the patch and was quite satisfied with the results, but upon a
>> >comment from colleagues I ran a few more tests and noticed (confirmed their
>> >hunch) that fwupd complains about not being able to get the free space in
>> >efivars:
>> >
>> >  # fwupdmgr get-devices | grep efivars
>> >  │     Update Error:       getting efivars free space is not supported
>> >  │ │   Update Error:       getting efivars free space is not supported
>> >  ...
>> >
>> >I was not able to establish whether that would prevent specific operations
>> >due to the HW I had available for such test.
>> 
>> fwupd will refuse to do some of its updates if it can't read the
>> efivars free space, in particular updates of the secure boot keyrings
>> like KEK/DB/DBX.
>
> In this case, corroborating with Sashiko findings, it is necessary to have
> a way to override that default in kernels with PREEMPT_RT enabled. To be used
> where this is required for firmware updates.
>

Indeed.