linux-kernel - Re: [RFC PATCH] efivarfs: Introduce efivarfs refresh remount

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Message-ID: <CAHk0HovnRgxrKu0uoj1x3XSB1vrTaGtMn-7iaoSR5Fs+=EYd5g@mail.gmail.com>
Date: Wed, 15 Jan 2025 22:49:23 +0800
From: Weizhao Ouyang <o451686892@...il.com>
To: James Bottomley <James.Bottomley@...senpartnership.com>
Cc: Jonathan Corbet <corbet@....net>, Jeremy Kerr <jk@...abs.org>, Ard Biesheuvel <ardb@...nel.org>, 
	Tim Schumacher <timschumi@....de>, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-efi@...r.kernel.org
Subject: Re: [RFC PATCH] efivarfs: Introduce efivarfs refresh remount

On Wed, Jan 15, 2025 at 10:34 PM James Bottomley
<James.Bottomley@...senpartnership.com> wrote:
>
> On Wed, 2025-01-15 at 22:14 +0800, Weizhao Ouyang wrote:
> > Currently, when setting efi variables through the runtime service,
> > efivarfs cannot sync variable updates properly. Introduce efivarfs
> > refresh remount to support efivarfs information updates from other
> > sources.
>
> What other sources could there possibly be?  While the Linux kernel has
> sole possession of the EFI RT interface after ExitBootServices has been
> called, nothing else should be able to update the variables except
> efivarfs.  This is a guarantee from UEFI so why do you think we can't
> rely on it?

One route that may exist is: drivers/firmware/efi/test/efi_test.c holds
some ioctls to call runtime service.

BR,
Weizhao

>
> Regards,
>
> James
>