linux-kernel - RE: [PATCH 1/1] Drivers: hv: Select CONFIG

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Message-ID:
 <SN6PR02MB4157773351091649D5AB5D42D446A@SN6PR02MB4157.namprd02.prod.outlook.com>
Date: Mon, 30 Jun 2025 20:46:51 +0000
From: Michael Kelley <mhklinux@...look.com>
To: "kys@...rosoft.com" <kys@...rosoft.com>, "haiyangz@...rosoft.com"
	<haiyangz@...rosoft.com>, "wei.liu@...nel.org" <wei.liu@...nel.org>,
	"decui@...rosoft.com" <decui@...rosoft.com>, "deller@....de" <deller@....de>,
	"javierm@...hat.com" <javierm@...hat.com>, "arnd@...db.de" <arnd@...db.de>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH 1/1] Drivers: hv: Select CONFIG_SYSFB only if EFI is
 enabled

From: mhkelley58@...il.com <mhkelley58@...il.com> Sent: Friday, June 13, 2025 4:01 PM
> 
> Commit 96959283a58d ("Drivers: hv: Always select CONFIG_SYSFB
> for Hyper-V guests") selects CONFIG_SYSFB for Hyper-V guests
> so that screen_info is available to the VMBus driver to get
> the location of the framebuffer in Generation 2 VMs. However,
> if CONFIG_HYPERV is enabled but CONFIG_EFI is not, a kernel
> link error results in ARM64 builds because screen_info is
> provided by the EFI firmware interface. While configuring
> an ARM64 Hyper-V guest without EFI isn't useful since EFI is
> required to boot, the configuration is still possible and
> the link error should be prevented.
> 
> Fix this by making the selection of CONFIG_SYSFB conditional
> on CONFIG_EFI being defined. For Generation 1 VMs on x86/x64,
> which don't use EFI, the additional condition is OK because
> such VMs get the framebuffer information via a mechanism
> that doesn't use screen_info.
> 
> Fixes: 96959283a58d ("Drivers: hv: Always select CONFIG_SYSFB for Hyper-V guests")
> Reported-by: Arnd Bergmann <arnd@...db.de>
> Closes: https://lore.kernel.org/linux-hyperv/20250610091810.2638058-1-arnd@kernel.org/

Arnd -- Can you give a "Reviewed-by:" or "Acked-by:" for this fix?  It
needs to get into linux-next and then into Linus' tree before we
get too late in the 6.16 release cycle.

Michael

> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202506080820.1wmkQufc-lkp@intel.com/
> Signed-off-by: Michael Kelley <mhklinux@...look.com>
> ---
>  drivers/hv/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
> index 1cd188b73b74..57623ca7f350 100644
> --- a/drivers/hv/Kconfig
> +++ b/drivers/hv/Kconfig
> @@ -9,7 +9,7 @@ config HYPERV
>  	select PARAVIRT
>  	select X86_HV_CALLBACK_VECTOR if X86
>  	select OF_EARLY_FLATTREE if OF
> -	select SYSFB if !HYPERV_VTL_MODE
> +	select SYSFB if EFI && !HYPERV_VTL_MODE
>  	help
>  	  Select this option to run Linux as a Hyper-V client operating
>  	  system.
> --
> 2.25.1
>