linux-kernel - Re: [PATCH v2] efi: add ovmf debug log driver

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Message-ID: <2mn65slwkwmjpeilma2isw7zgabdmda4rhpqjiutwdwqno2wrh@zghymlce2fiy>
Date: Wed, 9 Jul 2025 16:17:50 +0200
From: Gerd Hoffmann <kraxel@...hat.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: linux-efi@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>, 
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] efi: add ovmf debug log driver

On Wed, Jul 09, 2025 at 03:58:58PM +0200, Krzysztof Kozlowski wrote:
> On 08/07/2025 14:56, Gerd Hoffmann wrote:
> > +MODULE_DESCRIPTION("OVMF debug log");
> > +MODULE_AUTHOR("Gerd Hoffmann <kraxel@...hat.com>");
> > +MODULE_LICENSE("GPL");
> > +MODULE_ALIAS("platform:ovmf_debug_log");
> > diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> > index db8c5c03d3a2..ac0a03ec3452 100644
> > --- a/drivers/firmware/efi/Kconfig
> > +++ b/drivers/firmware/efi/Kconfig
> > @@ -263,6 +263,14 @@ config EFI_COCO_SECRET
> >  	  virt/coco/efi_secret module to access the secrets, which in turn
> >  	  allows userspace programs to access the injected secrets.
> >  
> > +config OVMF_DEBUG_LOG
> > +	tristate "Expose OVMF firmware debug log via sysfs"
> > +	depends on EFI
> > +	help
> > +	  Recent OVMF versions (edk2-stable202508 + newer) can write
> > +	  their debug log to a memory buffer.  This driver exposes the
> > +	  log content via sysfs (/sys/firmware/efi/ovmf_debug_log).
> 
> Where did you document new ABI?

The log buffer header struct is documented in the header file for the
edk2 code:
https://github.com/tianocore/edk2/blob/master/OvmfPkg/Include/Library/MemDebugLogLib.h

take care,
  Gerd