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

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Message-Id: <20250613230059.380483-1-mhklinux@outlook.com>
Date: Fri, 13 Jun 2025 16:00:59 -0700
From: mhkelley58@...il.com
To: kys@...rosoft.com,
	haiyangz@...rosoft.com,
	wei.liu@...nel.org,
	decui@...rosoft.com,
	deller@....de,
	javierm@...hat.com,
	arnd@...db.de
Cc: linux-kernel@...r.kernel.org,
	linux-hyperv@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH 1/1] Drivers: hv: Select CONFIG_SYSFB only if EFI is enabled

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>
---
 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