linux-kernel - [tip: x86/kconfig] x86/kconfig/defconfig: Enable CONFIG_DRM_FBDEV

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Message-ID: <174988686864.406.18261837065176549919.tip-bot2@tip-bot2>
Date: Sat, 14 Jun 2025 07:41:08 -0000
From: "tip-bot2 for Ingo Molnar" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Michael Kelley <mhklinux@...look.com>, Ingo Molnar <mingo@...nel.org>,
 Vitaly Kuznetsov <vkuznets@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
 Ard Biesheuvel <ardb@...nel.org>, Arnd Bergmann <arnd@...db.de>,
 David Woodhouse <dwmw@...zon.co.uk>, "H. Peter Anvin" <hpa@...or.com>,
 jgross@...e.com, Linus Torvalds <torvalds@...ux-foundation.org>,
 Masahiro Yamada <yamada.masahiro@...ionext.com>,
 Michal Marek <michal.lkml@...kovi.net>, linux-kernel@...r.kernel.org,
 x86@...nel.org
Subject:
 [tip: x86/kconfig] x86/kconfig/defconfig: Enable CONFIG_DRM_FBDEV_EMULATION=y

The following commit has been merged into the x86/kconfig branch of tip:

Commit-ID:     7ce421edd9fc5a762aeb625cc682cb793ec859d7
Gitweb:        https://git.kernel.org/tip/7ce421edd9fc5a762aeb625cc682cb793ec859d7
Author:        Ingo Molnar <mingo@...nel.org>
AuthorDate:    Sat, 14 Jun 2025 09:10:55 +02:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Sat, 14 Jun 2025 09:30:35 +02:00

x86/kconfig/defconfig: Enable CONFIG_DRM_FBDEV_EMULATION=y

Michael Kelley reported that the x86 defconfig *almost* works
well on Hyper-V guests out of box, with the exception of
console support:

 > I built and tested a Hyper-V guest with defconfig. The Hyper-V storage
 > and keyboard drivers are pulled in automatically. [...]
 >
 > But the Linux console for each Hyper-V guest is a synthetic graphics
 > console, and that didn't work with the DRM_HYPERV driver. Missing
 > the console pretty much kills any usefulness. DRM doesn't have
 > Linux console support, so it needs CONFIG_DRM_FBDEV_EMULATION
 > to be set, and defconfig doesn't have it.

So enable CONFIG_DRM_FBDEV_EMULATION.

Also enable the dependent CONFIG_FRAMEBUFFER_CONSOLE_ROTATION option
(disabled by default), as all major Linux distros have it enabled,
probably as a sysadmin quality-of-life option:

	.config.distro.debian.x86_32:     CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
	.config.distro.fedora.generic:    CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
	.config.distro.opensuse.default:  CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
	.config.distro.rhel.generic:      CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
	.config.distro.ubuntu:            CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y

There's no measurable build time impact within ~1% stddev:

  $ perf stat --null --repeat 3 --sync --pre='make clean >/dev/null' make -j128 bzImage >/dev/null

  Performance counter stats for 'make -j128 bzImage' (3 runs):

  # before:         33.759 +- 0.286 seconds time elapsed  ( +-  0.85% )
  # after:          33.593 +- 0.314 seconds time elapsed  ( +-  0.94% )

Suggested-by: Michael Kelley <mhklinux@...look.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ard Biesheuvel <ardb@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: David Woodhouse <dwmw@...zon.co.uk>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Jürgen Groß <jgross@...e.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc: Michal Marek <michal.lkml@...kovi.net>
Cc: linux-kernel@...r.kernel.org
Link: https://lore.kernel.org/r/SN6PR02MB4157B1676A6284ECD21E494FD490A@SN6PR02MB4157.namprd02.prod.outlook.com # Discussion
---
 arch/x86/configs/i386_defconfig   | 2 ++
 arch/x86/configs/x86_64_defconfig | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/arch/x86/configs/i386_defconfig b/arch/x86/configs/i386_defconfig
index aeba958..39a660d 100644
--- a/arch/x86/configs/i386_defconfig
+++ b/arch/x86/configs/i386_defconfig
@@ -239,8 +239,10 @@ CONFIG_AGP=y
 CONFIG_AGP_AMD64=y
 CONFIG_AGP_INTEL=y
 CONFIG_DRM=y
+CONFIG_DRM_FBDEV_EMULATION=y
 CONFIG_DRM_VIRTIO_GPU=y
 CONFIG_DRM_HYPERV=y
+CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
 CONFIG_SOUND=y
 CONFIG_SND=y
 CONFIG_SND_HRTIMER=y
diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig
index c20100d..b5dc26f 100644
--- a/arch/x86/configs/x86_64_defconfig
+++ b/arch/x86/configs/x86_64_defconfig
@@ -116,6 +116,7 @@ CONFIG_ANON_VMA_NAME=y
 CONFIG_USERFAULTFD=y
 CONFIG_LRU_GEN=y
 CONFIG_LRU_GEN_ENABLED=y
+# CONFIG_DAMON is not set
 CONFIG_NET=y
 CONFIG_PACKET=y
 CONFIG_XFRM_USER=y
@@ -248,8 +249,10 @@ CONFIG_AGP=y
 CONFIG_AGP_AMD64=y
 CONFIG_AGP_INTEL=y
 CONFIG_DRM=y
+CONFIG_DRM_FBDEV_EMULATION=y
 CONFIG_DRM_VIRTIO_GPU=y
 CONFIG_DRM_HYPERV=y
+CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y
 CONFIG_SOUND=y
 CONFIG_SND=y
 CONFIG_SND_HRTIMER=y