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

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Message-ID: <aG7vy8qECWqIz-7T@liuwe-devbox-ubuntu-v2.lamzopl0uupeniq2etz1fddiyg.xx.internal.cloudapp.net>
Date: Wed, 9 Jul 2025 22:40:11 +0000
From: Wei Liu <wei.liu@...nel.org>
To: mhklinux@...look.com
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
	decui@...rosoft.com, deller@....de, javierm@...hat.com,
	arnd@...db.de, linux-kernel@...r.kernel.org,
	linux-hyperv@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 1/1] Drivers: hv: Select CONFIG_SYSFB only if EFI is
 enabled

On Fri, Jun 13, 2025 at 04:00:59PM -0700, mhkelley58@...il.com wrote:
> From: Michael Kelley <mhklinux@...look.com>
> 
> 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/
> 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>

Applied to hyperv-fixes. Thanks!