RE: [PATCH] mefi: add dynamic control interface for EFI runtime services

[Chang, Junxiao]

>From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
>On 2026-07-23 08:37:23 [+0200], Ard Biesheuvel wrote:
>> (cc Sebastian)
>Thanks.
>
>> On Sat, 4 Jul 2026, at 02:33, Junxiao Chang wrote:
>> > b/Documentation/admin-guide/kernel-parameters.txt
>>
>> I'd prefer not to add a command line option for this. If the sysfs
>> control is useful, we can enable it unconditionally, or depend on PREEMPT_RT.
>
>If we do this enable/ disable at runtime, could we name if "runtime_enable" or
>"enabled" instead "dynamic_enable"?
Sure, I will update it.

>We could also have the =noruntime option as an initial off switch which could be
>overwritten at runtime to enable it temporary.
>This probably benefits only efivars since everything else (like efi-rtc) remains non-
>functional or broken (if enabled/ disabled at runtime).
It seems that it needs a big change to implement it. Maybe it could be implemented in a separate change in future?

>
>We have this thing where the efi-runtime workqueue can be limited to a certain
>CPU in case it helps. But then I learned then certain EFI versions do block all other
>CPUs while the one CPU is performing a EFI invocation…
Yes. It could introduce 2ms delay for all CPUs.