From nobody Fri Oct 10 09:16:42 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AEB2D23DE for ; Sat, 14 Jun 2025 07:32:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749886341; cv=none; b=ItV2LXF/xD4ov8krEGYxOKGmna/v03v/y5XkO3WwgsyvsC8EJxi7WUtEaJ5CFlcvpxumEO9VtaIRTVkYBgdQvsCFqSqtWxN1G14LyizVkOLg021XYJv5OFhu9KMFB+JN2/3fZmbnzAH4ShNb+MCZKM0rkPxNlPdsgXfuVLGJKbQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749886341; c=relaxed/simple; bh=czQV28/YkuDiLpcPrU879HwkRtZV6i6qIUU/ROMxJXY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Y4qtdbjKJoY3Ar8tPV8GKP29ynbIAoAAw6o4rCPtJNS1AZQ+lzF8BnQR6bveSRLy8f/hIGurnj2Nu7P5kwdnTX1T4rRMP+TzBXV18NeCd8GeD+31SNPogDn8hsnSjCwqDdZkcMSLKcB5ksIuoDKJVU5AuVG9l8M4R8+JXAYicLY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mInjfLnp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mInjfLnp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4FE33C4CEEB; Sat, 14 Jun 2025 07:32:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749886341; bh=czQV28/YkuDiLpcPrU879HwkRtZV6i6qIUU/ROMxJXY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mInjfLnpriobneFm/E30U2RvhasZwtrEo6cTbxmsNPUNZr7nLU6tweTAaGWsPDj44 kGepzSAeHUPqvfDbcsWdCo18m4iGiQ9QJgCw9TZ+rHhEAXgHNuAgKnNhH5P0IsCMlZ haZxofniuuwPxNt9ng2l3cCnR6mC+ZYJsD98srBq4jiruVjLDfAfYU4qmQhdjaKRxf gaN2dM7PtNliNPFP1LcILSh3npRjgX3TPUsRiR33CIZQ1xIyeuBRtzlNAuZOKxW5AE 9DkOz9EZFMgX5RT1K7Kt5uFmKxGH3vL27gacnLi0GuRTL42A0Bo8ule67UY6A78WYu wvoNxjSbo0Adg== Date: Sat, 14 Jun 2025 09:32:14 +0200 From: Ingo Molnar To: Vitaly Kuznetsov Cc: Michael Kelley , "linux-kernel@vger.kernel.org" , "H . Peter Anvin" , Linus Torvalds , Peter Zijlstra , Borislav Petkov , Thomas Gleixner , =?iso-8859-1?Q?J=FCrgen_Gro=DF?= , "Kirill A . Shutemov" , Ard Biesheuvel , Arnd Bergmann , Carlos Bilbao , David Woodhouse , Elena Reshetova , Fei Li , Jan Kiszka , Masahiro Yamada , Michal Marek , Paolo Bonzini , Sean Christopherson , Stefano Stabellini Subject: [PATCH] x86/kconfig/defconfig: Enable CONFIG_DRM_FBDEV_EMULATION=y Message-ID: References: <20250515132719.31868-1-mingo@kernel.org> <20250515132719.31868-8-mingo@kernel.org> <87o6vtnf8m.fsf@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <87o6vtnf8m.fsf@redhat.com> Content-Type: text/plain; charset="utf-8" * Vitaly Kuznetsov wrote: > Michael Kelley writes: >=20 > > From: Ingo Molnar Sent: Thursday, May 15, 2025 6:27 = AM > >>=20 > >> Since the x86 defconfig aims to be a distro kernel work-alike with > >> fewer drivers and a shorter build time, refresh all the virtualization > >> guest Kconfig features, enabling paravirt spinlocks, and > >> enabling the guest support code for the following guests: > >>=20 > >> - Xen > >> - Xen_PVH > >> - Jailhouse > >> - ACRN > >> - Intel TDX > >> - Hyper-V > > > > I built and tested a Hyper-V guest with defconfig. The Hyper-V storage > > and keyboard drivers are pulled in automatically, so my previous > > comment about them being "missing" is moot. > > > > 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=20 > > Linux console support, so it needs CONFIG_DRM_FBDEV_EMULATION > > to be set, and defconfig doesn't have it. > > > > So either CONFIG_DRM_FBDEV_EMULATION needs to be added, or > > defconfig should switch to the older HYPERV_FB driver. I think we'd > > rather do the former. Vitaly -- any thoughts? > > >=20 > Yea, my vote goes to the same option: let's enable > CONFIG_DRM_FBDEV_EMULATION. Okay - I've addressed the enabling of this option separately in: 7ce421edd9fc ("x86/kconfig/defconfig: Enable CONFIG_DRM_FBDEV_EMULATION= =3Dy") Also attached below. Thanks, Ingo =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D> From: Ingo Molnar Date: Sat, 14 Jun 2025 09:10:55 +0200 Subject: [PATCH] x86/kconfig/defconfig: Enable CONFIG_DRM_FBDEV_EMULATION= =3Dy 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=3Dy .config.distro.fedora.generic: CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=3Dy .config.distro.opensuse.default: CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=3Dy .config.distro.rhel.generic: CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=3Dy .config.distro.ubuntu: CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=3Dy There's no measurable build time impact within ~1% stddev: $ perf stat --null --repeat 3 --sync --pre=3D'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 Signed-off-by: Ingo Molnar Acked-by: Vitaly Kuznetsov Cc: Peter Zijlstra Cc: Ard Biesheuvel Cc: Arnd Bergmann Cc: David Woodhouse Cc: H. Peter Anvin Cc: J=C3=BCrgen Gro=C3=9F Cc: Linus Torvalds Cc: Masahiro Yamada Cc: Michal Marek Cc: linux-kernel@vger.kernel.org Link: https://lore.kernel.org/r/SN6PR02MB4157B1676A6284ECD21E494FD490A@SN6P= R02MB4157.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_defcon= fig index aeba95893086..39a660d71a0a 100644 --- a/arch/x86/configs/i386_defconfig +++ b/arch/x86/configs/i386_defconfig @@ -239,8 +239,10 @@ CONFIG_AGP=3Dy CONFIG_AGP_AMD64=3Dy CONFIG_AGP_INTEL=3Dy CONFIG_DRM=3Dy +CONFIG_DRM_FBDEV_EMULATION=3Dy CONFIG_DRM_VIRTIO_GPU=3Dy CONFIG_DRM_HYPERV=3Dy +CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=3Dy CONFIG_SOUND=3Dy CONFIG_SND=3Dy CONFIG_SND_HRTIMER=3Dy diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_de= fconfig index c20100d77387..b5dc26fb715a 100644 --- a/arch/x86/configs/x86_64_defconfig +++ b/arch/x86/configs/x86_64_defconfig @@ -116,6 +116,7 @@ CONFIG_ANON_VMA_NAME=3Dy CONFIG_USERFAULTFD=3Dy CONFIG_LRU_GEN=3Dy CONFIG_LRU_GEN_ENABLED=3Dy +# CONFIG_DAMON is not set CONFIG_NET=3Dy CONFIG_PACKET=3Dy CONFIG_XFRM_USER=3Dy @@ -248,8 +249,10 @@ CONFIG_AGP=3Dy CONFIG_AGP_AMD64=3Dy CONFIG_AGP_INTEL=3Dy CONFIG_DRM=3Dy +CONFIG_DRM_FBDEV_EMULATION=3Dy CONFIG_DRM_VIRTIO_GPU=3Dy CONFIG_DRM_HYPERV=3Dy +CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=3Dy CONFIG_SOUND=3Dy CONFIG_SND=3Dy CONFIG_SND_HRTIMER=3Dy