From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Arnd Bergmann" Subject: Re: [PATCH v2 1/9] vgacon: rework Kconfig dependencies Date: Fri, 21 Jul 2023 10:26:30 +0200 Message-ID: <19631e74-415e-4dcb-b79d-33dcf03d2dfc@app.fastmail.com> References: <20230719123944.3438363-1-arnd@kernel.org> <20230719123944.3438363-2-arnd@kernel.org> <87pm4lj1w3.fsf@mail.lhotse> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm2; t=1689928040; x=1690014440; bh=V8 kkxioRFPjR/pcGqI7bYcicee1af9QaKC3pDwPABSg=; b=cSu25aofj3k78Gwvjn AeApNXcPQ4m0EkJR+F/FR6X0iWUO4WSNdIIXBNu9IuKLJRziOlSFRwDBU8XHxTAZ qFvfpzf6Fqcsui64BX/auOaUT8DpTf55Um6d6mIrhtX90E7pAWUkD4FxYpYGJo3R cJ23vzSYXksDNzV5a5SVkd3auBPf4sTFsIbC5WfiZtnbkhUaTGjWxwHEZjc5dj4Z ExxSxCQnOdr8Nh2a8NO8ayVRWbjLPzFLtRExpI2Wkb9vg6QauJCHb4+5i+FSpnXM r/zD/innoFirhLlgq9POHdmFW+DsxQzLUq4o9sf1LEqMG3qLnDEwxNS26mrQY/3k za2w== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; t=1689928040; x=1690014440; bh=V8kkxioRFPjR/ pcGqI7bYcicee1af9QaKC3pDwPABSg=; b=JLTw/YwFC4sBp4eez9+aKjZwfdUxH oR/mZBQ+L1gJ4Cpfz1EgHzlgGEdvDo1MQAN2+5JUTAP9maAMGaPzy4rh/1QP/gr2 i3AVkB7R92HU90NWLS3VB4VHT3pu4ItP6yrpMz949odIs4AiptZGzzPE5Jyf/oUP 8RHnAj5WamxgQToMEXU+DdHI2Wgd+dn4kyMrYsuhj6H/9TK7zBBNpZ5l67fbVHG8 chitq7Y51/9QRvvtx52pkfeh9rKiXrGsRxKVZ0iUK3MGBTXtds+sd+526B6ccQvb E5dGv4p2vxusjFWvSyTWybP4Ci3VfrkuumVEROmmRFBnEf3CI0ZkrLLag== In-Reply-To: <87pm4lj1w3.fsf@mail.lhotse> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michael Ellerman , Arnd Bergmann , linux-fbdev@vger.kernel.org, Thomas Zimmermann , Helge Deller , Javier Martinez Canillas Cc: "David S . Miller" , "K. Y. Srinivasan" , Ard Biesheuvel , Borislav Petkov , Brian Cain , Catalin Marinas , Christophe Leroy , Daniel Vetter , Dave Hansen , Dave Airlie , Deepak Rawat , Dexuan Cui , Dinh Nguyen , Greg Kroah-Hartman , guoren , Haiyang Zhang , Huacai Chen , Ingo Molnar , John Paul Adrian Glaubitz On Fri, Jul 21, 2023, at 06:59, Michael Ellerman wrote: > Arnd Bergmann writes: >> From: Arnd Bergmann >> >> The list of dependencies here is phrased as an opt-out, but this is missing >> a lot of architectures that don't actually support VGA consoles, and some >> of the entries are stale: >> >> - powerpc used to support VGA consoles in the old arch/ppc codebase, but >> the merged arch/powerpc never did > > Not disputing this, but how did you come to that conclusion? I grepped > around and couldn't convince myself whether it can work on powerpc or > not. ie. currently it's possible to enable CONFIG_VGA_CONSOLE and > powerpc does have a struct screen_info defined which seems like it would > allow vgacon_startup() to complete. The VGA console needs both screen_info and vga_con to work. In arch/ppc we had both, but in arch/powerpc we only retained the screen_info: $ git grep vga_con v2.6.26 -- arch/ppc arch/ppc64 arch/powerpc v2.6.26:arch/ppc/platforms/pplus.c: conswitchp = &vga_con; v2.6.26:arch/ppc/platforms/prep_setup.c: conswitchp = &vga_con; so after arch/ppc was removed, this became impossible to use on both pplus and prep. These two platforms were also (as far as I can tell) the only ones to support vga16fb as an alternative to vgacon, but both platforms were removed later on. > My only concern is that someone could be using it with Qemu? I have not yet ruled out anyone using vga16fb on qemu before commit 0db5b61e0dc07 ("fbdev/vga16fb: Create EGA/VGA devices in sysfb code"), but I can see that this has been broken for 12 months without anyone complaining about it, since vga16fb no longer works with the "orig_video_isVGA == 1" setting in arch/powerpc (the device is not created). In the qemu sources, I see five powerpc machines that intialize VGA support: mac_newworld, mac_oldworld, pegasos2, prep, and spapr. I think we can exclude prep (which was removed from the kernel) and spapr (64-bit VGA_MAP_MEM() looks broken). I think the macs always come up in graphical mode and only use offb/atifb/rivafb/matroxfb but not vga16fb that would require running the x86 VGA BIOS initialization. I suppose it's possible to use vga16fb (not vgacon) with "qemu-system-ppc -M pegasos2 -vga std" if that still boots at all. Support for pegasos2 hardware appears to have been removed with commit 04debf21fa174 ("powerpc: Remove core support for Marvell mv64x60 hostbridges"), but it's possible that this did not break qemu support if that only uses devices under arch/powerpc/platforms/chrp/pci.c. I could not get it to boot, but did not try very hard. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BBD7CC00528 for ; Fri, 21 Jul 2023 08:27:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230249AbjGUI1Z (ORCPT ); Fri, 21 Jul 2023 04:27:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230062AbjGUI1Y (ORCPT ); Fri, 21 Jul 2023 04:27:24 -0400 Received: from new3-smtp.messagingengine.com (new3-smtp.messagingengine.com [66.111.4.229]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EB5E1F0; Fri, 21 Jul 2023 01:27:22 -0700 (PDT) Received: from compute6.internal (compute6.nyi.internal [10.202.2.47]) by mailnew.nyi.internal (Postfix) with ESMTP id CDE4D58026A; Fri, 21 Jul 2023 04:27:21 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute6.internal (MEProxy); Fri, 21 Jul 2023 04:27:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm2; t=1689928041; x=1689935241; bh=V8 kkxioRFPjR/pcGqI7bYcicee1af9QaKC3pDwPABSg=; b=b9mWPVKTa+C0qxGJVm gVTKr5SnuCufxByEgtuEiTC/HjonV9yPvhgncSRQ0wUrLNE7orD78Rw7ohjT0q3C c0X7wLA5W1uO4gHBmiwybGJLQQ7SrEMtBGvFZKQaT/Y0wzIbtxoIfYUgm9pO+XSJ 6I08Fx8oDJAOPBCXHuGFZFeWb1RYZSXq09xFAfH85OnLe5l+htjQL+F/B4Y6gUvs ut/AOfdKRpwcHg/s2ox2GO/l5Ce/RBfBcnmaRO/F69sTDvSKTTvAQwHRFh24O6bw V6xDq+6cg4uZot5gbimNNmCu9SHpdf5MFTDtGh/g5OFBKMn02cs7TznQk+C9/i4Y dRwg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; t=1689928041; x=1689935241; bh=V8kkxioRFPjR/ pcGqI7bYcicee1af9QaKC3pDwPABSg=; b=unYn7VUfp/o2gT07nbqvQ5lIW9kBd mBnKota720DDPc/oG1aRttW/D+crNdOAUEl9St9nonOTjtR5EHZ/ERbVU6RS/8a9 h60zyLUrHFHJTeNLWeadDvND/TVlwE64W4ER4jaFI7yfcqQcM9JFFXLEQa8gKTAm 2NneyWtfI14HUK6C7gElYEN39Z+C3ZEMkQn2ZM6gax2xS8UlImkh100FKtZaGPhv lQk5OR6Mr17MQHWJ9UIPy7fklXcZo7AkC1hU9D8FRcT0DoHGZ1ht5evHlxZxLnfx AEw3wiOX0qizHBpHqwTM2HVi93NRv6iA2yioBToovm3YnDAmy38mo5uCg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrhedvgddtudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpefofgggkfgjfhffhffvvefutgesthdtredtreertdenucfhrhhomhepfdetrhhn ugcuuegvrhhgmhgrnhhnfdcuoegrrhhnugesrghrnhgusgdruggvqeenucggtffrrghtth gvrhhnpeffheeugeetiefhgeethfejgfdtuefggeejleehjeeutefhfeeggefhkedtkeet ffenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegrrh hnugesrghrnhgusgdruggv X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id AB365B60089; Fri, 21 Jul 2023 04:27:19 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-531-gfdfa13a06d-fm-20230703.001-gfdfa13a0 Mime-Version: 1.0 Message-Id: <19631e74-415e-4dcb-b79d-33dcf03d2dfc@app.fastmail.com> In-Reply-To: <87pm4lj1w3.fsf@mail.lhotse> References: <20230719123944.3438363-1-arnd@kernel.org> <20230719123944.3438363-2-arnd@kernel.org> <87pm4lj1w3.fsf@mail.lhotse> Date: Fri, 21 Jul 2023 10:26:30 +0200 From: "Arnd Bergmann" To: "Michael Ellerman" , "Arnd Bergmann" , linux-fbdev@vger.kernel.org, "Thomas Zimmermann" , "Helge Deller" , "Javier Martinez Canillas" Cc: "David S . Miller" , "K. Y. Srinivasan" , "Ard Biesheuvel" , "Borislav Petkov" , "Brian Cain" , "Catalin Marinas" , "Christophe Leroy" , "Daniel Vetter" , "Dave Hansen" , "Dave Airlie" , "Deepak Rawat" , "Dexuan Cui" , "Dinh Nguyen" , "Greg Kroah-Hartman" , guoren , "Haiyang Zhang" , "Huacai Chen" , "Ingo Molnar" , "John Paul Adrian Glaubitz" , "Khalid Aziz" , "Linus Walleij" , "Matt Turner" , "Max Filippov" , "Nicholas Piggin" , "Palmer Dabbelt" , "Russell King" , "Thomas Bogendoerfer" , "Thomas Gleixner" , "WANG Xuerui" , "Wei Liu" , "Will Deacon" , x86@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org, "linux-csky@vger.kernel.org" , linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH v2 1/9] vgacon: rework Kconfig dependencies Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Fri, Jul 21, 2023, at 06:59, Michael Ellerman wrote: > Arnd Bergmann writes: >> From: Arnd Bergmann >> >> The list of dependencies here is phrased as an opt-out, but this is missing >> a lot of architectures that don't actually support VGA consoles, and some >> of the entries are stale: >> >> - powerpc used to support VGA consoles in the old arch/ppc codebase, but >> the merged arch/powerpc never did > > Not disputing this, but how did you come to that conclusion? I grepped > around and couldn't convince myself whether it can work on powerpc or > not. ie. currently it's possible to enable CONFIG_VGA_CONSOLE and > powerpc does have a struct screen_info defined which seems like it would > allow vgacon_startup() to complete. The VGA console needs both screen_info and vga_con to work. In arch/ppc we had both, but in arch/powerpc we only retained the screen_info: $ git grep vga_con v2.6.26 -- arch/ppc arch/ppc64 arch/powerpc v2.6.26:arch/ppc/platforms/pplus.c: conswitchp = &vga_con; v2.6.26:arch/ppc/platforms/prep_setup.c: conswitchp = &vga_con; so after arch/ppc was removed, this became impossible to use on both pplus and prep. These two platforms were also (as far as I can tell) the only ones to support vga16fb as an alternative to vgacon, but both platforms were removed later on. > My only concern is that someone could be using it with Qemu? I have not yet ruled out anyone using vga16fb on qemu before commit 0db5b61e0dc07 ("fbdev/vga16fb: Create EGA/VGA devices in sysfb code"), but I can see that this has been broken for 12 months without anyone complaining about it, since vga16fb no longer works with the "orig_video_isVGA == 1" setting in arch/powerpc (the device is not created). In the qemu sources, I see five powerpc machines that intialize VGA support: mac_newworld, mac_oldworld, pegasos2, prep, and spapr. I think we can exclude prep (which was removed from the kernel) and spapr (64-bit VGA_MAP_MEM() looks broken). I think the macs always come up in graphical mode and only use offb/atifb/rivafb/matroxfb but not vga16fb that would require running the x86 VGA BIOS initialization. I suppose it's possible to use vga16fb (not vgacon) with "qemu-system-ppc -M pegasos2 -vga std" if that still boots at all. Support for pegasos2 hardware appears to have been removed with commit 04debf21fa174 ("powerpc: Remove core support for Marvell mv64x60 hostbridges"), but it's possible that this did not break qemu support if that only uses devices under arch/powerpc/platforms/chrp/pci.c. I could not get it to boot, but did not try very hard. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A52F6C0015E for ; Fri, 21 Jul 2023 08:27:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Subject:Cc:To:From:Date:References: In-Reply-To:Message-Id:Mime-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=wYRZlzS2ZiBPmHbeI8hteS1ho5w84oZh5VWlcnKGZ/w=; b=cwuKaSuHvKS6Fi fbVb0te6SQVidy69kDUAqGpAk6SIJ51hvl9QZpbLVOhblWeP/QEEI/ZZkrxrfCsWMkyJGvX0P1Ke9 mFAYWJDEA2DjSkTRD2LW1y1szIja2kO4EUfeNynaYQz0PmhezfVJI2L2xtNZWWeHR5mAoO2ABm/Ng NtXa9k09DTBsiBaDQoArBe9DlsFvE3CbJ3tE9+YZTZFaogjjYgd2lFMDn1WuVzPFGgdtSPG/qwr5d XDhtOKJ1ywX41lDnXOqHYK2V8ZL/RXDoxQMCquhULbzp5Dty1/COn7bialG1RzbjCnFVYt00gjrO3 ICvvVqO5rB423ajE09+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qMlU2-00DMiu-01; Fri, 21 Jul 2023 08:27:30 +0000 Received: from new3-smtp.messagingengine.com ([66.111.4.229]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qMlTy-00DMgq-09; Fri, 21 Jul 2023 08:27:27 +0000 Received: from compute6.internal (compute6.nyi.internal [10.202.2.47]) by mailnew.nyi.internal (Postfix) with ESMTP id CDE4D58026A; Fri, 21 Jul 2023 04:27:21 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute6.internal (MEProxy); Fri, 21 Jul 2023 04:27:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm2; t=1689928041; x=1689935241; bh=V8 kkxioRFPjR/pcGqI7bYcicee1af9QaKC3pDwPABSg=; b=b9mWPVKTa+C0qxGJVm gVTKr5SnuCufxByEgtuEiTC/HjonV9yPvhgncSRQ0wUrLNE7orD78Rw7ohjT0q3C c0X7wLA5W1uO4gHBmiwybGJLQQ7SrEMtBGvFZKQaT/Y0wzIbtxoIfYUgm9pO+XSJ 6I08Fx8oDJAOPBCXHuGFZFeWb1RYZSXq09xFAfH85OnLe5l+htjQL+F/B4Y6gUvs ut/AOfdKRpwcHg/s2ox2GO/l5Ce/RBfBcnmaRO/F69sTDvSKTTvAQwHRFh24O6bw V6xDq+6cg4uZot5gbimNNmCu9SHpdf5MFTDtGh/g5OFBKMn02cs7TznQk+C9/i4Y dRwg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; t=1689928041; x=1689935241; bh=V8kkxioRFPjR/ pcGqI7bYcicee1af9QaKC3pDwPABSg=; b=unYn7VUfp/o2gT07nbqvQ5lIW9kBd mBnKota720DDPc/oG1aRttW/D+crNdOAUEl9St9nonOTjtR5EHZ/ERbVU6RS/8a9 h60zyLUrHFHJTeNLWeadDvND/TVlwE64W4ER4jaFI7yfcqQcM9JFFXLEQa8gKTAm 2NneyWtfI14HUK6C7gElYEN39Z+C3ZEMkQn2ZM6gax2xS8UlImkh100FKtZaGPhv lQk5OR6Mr17MQHWJ9UIPy7fklXcZo7AkC1hU9D8FRcT0DoHGZ1ht5evHlxZxLnfx AEw3wiOX0qizHBpHqwTM2HVi93NRv6iA2yioBToovm3YnDAmy38mo5uCg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrhedvgddtudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpefofgggkfgjfhffhffvvefutgesthdtredtreertdenucfhrhhomhepfdetrhhn ugcuuegvrhhgmhgrnhhnfdcuoegrrhhnugesrghrnhgusgdruggvqeenucggtffrrghtth gvrhhnpeffheeugeetiefhgeethfejgfdtuefggeejleehjeeutefhfeeggefhkedtkeet ffenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegrrh hnugesrghrnhgusgdruggv X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id AB365B60089; Fri, 21 Jul 2023 04:27:19 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-531-gfdfa13a06d-fm-20230703.001-gfdfa13a0 Mime-Version: 1.0 Message-Id: <19631e74-415e-4dcb-b79d-33dcf03d2dfc@app.fastmail.com> In-Reply-To: <87pm4lj1w3.fsf@mail.lhotse> References: <20230719123944.3438363-1-arnd@kernel.org> <20230719123944.3438363-2-arnd@kernel.org> <87pm4lj1w3.fsf@mail.lhotse> Date: Fri, 21 Jul 2023 10:26:30 +0200 From: "Arnd Bergmann" To: "Michael Ellerman" , "Arnd Bergmann" , linux-fbdev@vger.kernel.org, "Thomas Zimmermann" , "Helge Deller" , "Javier Martinez Canillas" Cc: "David S . Miller" , "K. Y. Srinivasan" , "Ard Biesheuvel" , "Borislav Petkov" , "Brian Cain" , "Catalin Marinas" , "Christophe Leroy" , "Daniel Vetter" , "Dave Hansen" , "Dave Airlie" , "Deepak Rawat" , "Dexuan Cui" , "Dinh Nguyen" , "Greg Kroah-Hartman" , guoren , "Haiyang Zhang" , "Huacai Chen" , "Ingo Molnar" , "John Paul Adrian Glaubitz" , "Khalid Aziz" , "Linus Walleij" , "Matt Turner" , "Max Filippov" , "Nicholas Piggin" , "Palmer Dabbelt" , "Russell King" , "Thomas Bogendoerfer" , "Thomas Gleixner" , "WANG Xuerui" , "Wei Liu" , "Will Deacon" , x86@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org, "linux-csky@vger.kernel.org" , linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-hyperv@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH v2 1/9] vgacon: rework Kconfig dependencies X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230721_012726_159114_10458E6C X-CRM114-Status: GOOD ( 20.35 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, Jul 21, 2023, at 06:59, Michael Ellerman wrote: > Arnd Bergmann writes: >> From: Arnd Bergmann >> >> The list of dependencies here is phrased as an opt-out, but this is missing >> a lot of architectures that don't actually support VGA consoles, and some >> of the entries are stale: >> >> - powerpc used to support VGA consoles in the old arch/ppc codebase, but >> the merged arch/powerpc never did > > Not disputing this, but how did you come to that conclusion? I grepped > around and couldn't convince myself whether it can work on powerpc or > not. ie. currently it's possible to enable CONFIG_VGA_CONSOLE and > powerpc does have a struct screen_info defined which seems like it would > allow vgacon_startup() to complete. The VGA console needs both screen_info and vga_con to work. In arch/ppc we had both, but in arch/powerpc we only retained the screen_info: $ git grep vga_con v2.6.26 -- arch/ppc arch/ppc64 arch/powerpc v2.6.26:arch/ppc/platforms/pplus.c: conswitchp = &vga_con; v2.6.26:arch/ppc/platforms/prep_setup.c: conswitchp = &vga_con; so after arch/ppc was removed, this became impossible to use on both pplus and prep. These two platforms were also (as far as I can tell) the only ones to support vga16fb as an alternative to vgacon, but both platforms were removed later on. > My only concern is that someone could be using it with Qemu? I have not yet ruled out anyone using vga16fb on qemu before commit 0db5b61e0dc07 ("fbdev/vga16fb: Create EGA/VGA devices in sysfb code"), but I can see that this has been broken for 12 months without anyone complaining about it, since vga16fb no longer works with the "orig_video_isVGA == 1" setting in arch/powerpc (the device is not created). In the qemu sources, I see five powerpc machines that intialize VGA support: mac_newworld, mac_oldworld, pegasos2, prep, and spapr. I think we can exclude prep (which was removed from the kernel) and spapr (64-bit VGA_MAP_MEM() looks broken). I think the macs always come up in graphical mode and only use offb/atifb/rivafb/matroxfb but not vga16fb that would require running the x86 VGA BIOS initialization. I suppose it's possible to use vga16fb (not vgacon) with "qemu-system-ppc -M pegasos2 -vga std" if that still boots at all. Support for pegasos2 hardware appears to have been removed with commit 04debf21fa174 ("powerpc: Remove core support for Marvell mv64x60 hostbridges"), but it's possible that this did not break qemu support if that only uses devices under arch/powerpc/platforms/chrp/pci.c. I could not get it to boot, but did not try very hard. Arnd _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4240CEB64DC for ; Fri, 21 Jul 2023 08:28:30 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=arndb.de header.i=@arndb.de header.a=rsa-sha256 header.s=fm2 header.b=b9mWPVKT; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=messagingengine.com header.i=@messagingengine.com header.a=rsa-sha256 header.s=fm3 header.b=unYn7VUf; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4R6jPS3HLnz3cBh for ; 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Fri, 21 Jul 2023 04:27:19 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-531-gfdfa13a06d-fm-20230703.001-gfdfa13a0 Mime-Version: 1.0 Message-Id: <19631e74-415e-4dcb-b79d-33dcf03d2dfc@app.fastmail.com> In-Reply-To: <87pm4lj1w3.fsf@mail.lhotse> References: <20230719123944.3438363-1-arnd@kernel.org> <20230719123944.3438363-2-arnd@kernel.org> <87pm4lj1w3.fsf@mail.lhotse> Date: Fri, 21 Jul 2023 10:26:30 +0200 From: "Arnd Bergmann" To: "Michael Ellerman" , "Arnd Bergmann" , linux-fbdev@vger.kernel.org, "Thomas Zimmermann" , "Helge Deller" , "Javier Martinez Canillas" Subject: Re: [PATCH v2 1/9] vgacon: rework Kconfig dependencies Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-hyperv@vger.kernel.org, x86@kernel.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Catalin Marinas , Linus Walleij , Dave Hansen , dri-devel@lists.freedesktop.org, linux-mips@vger.kernel.org, Max Filippov , linux-efi@vger.kernel.org, guoren , "linux-csky@vger.kernel.org" , sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, WANG Xuerui , "K. Y. Srinivasan" , Dave Airlie , Ard Biesheuvel , Wei Liu , Will Deacon , Huacai Chen , Dexuan Cui , Russell King , Deepak Rawat , Ingo Molnar , Matt Turner , Haiyang Zhang , Nicholas Piggin , Boris lav Petkov , loongarch@lists.linux.dev, John Paul Adrian Glaubitz , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Khalid Aziz , Brian Cain , Thomas Bogendoerfer , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Dinh Nguyen , linux-riscv@lists.infradead.org, Palmer Dabbelt , Daniel Vetter , linux-alpha@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "David S . Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Jul 21, 2023, at 06:59, Michael Ellerman wrote: > Arnd Bergmann writes: >> From: Arnd Bergmann >> >> The list of dependencies here is phrased as an opt-out, but this is missing >> a lot of architectures that don't actually support VGA consoles, and some >> of the entries are stale: >> >> - powerpc used to support VGA consoles in the old arch/ppc codebase, but >> the merged arch/powerpc never did > > Not disputing this, but how did you come to that conclusion? I grepped > around and couldn't convince myself whether it can work on powerpc or > not. ie. currently it's possible to enable CONFIG_VGA_CONSOLE and > powerpc does have a struct screen_info defined which seems like it would > allow vgacon_startup() to complete. The VGA console needs both screen_info and vga_con to work. In arch/ppc we had both, but in arch/powerpc we only retained the screen_info: $ git grep vga_con v2.6.26 -- arch/ppc arch/ppc64 arch/powerpc v2.6.26:arch/ppc/platforms/pplus.c: conswitchp = &vga_con; v2.6.26:arch/ppc/platforms/prep_setup.c: conswitchp = &vga_con; so after arch/ppc was removed, this became impossible to use on both pplus and prep. These two platforms were also (as far as I can tell) the only ones to support vga16fb as an alternative to vgacon, but both platforms were removed later on. > My only concern is that someone could be using it with Qemu? I have not yet ruled out anyone using vga16fb on qemu before commit 0db5b61e0dc07 ("fbdev/vga16fb: Create EGA/VGA devices in sysfb code"), but I can see that this has been broken for 12 months without anyone complaining about it, since vga16fb no longer works with the "orig_video_isVGA == 1" setting in arch/powerpc (the device is not created). In the qemu sources, I see five powerpc machines that intialize VGA support: mac_newworld, mac_oldworld, pegasos2, prep, and spapr. I think we can exclude prep (which was removed from the kernel) and spapr (64-bit VGA_MAP_MEM() looks broken). I think the macs always come up in graphical mode and only use offb/atifb/rivafb/matroxfb but not vga16fb that would require running the x86 VGA BIOS initialization. I suppose it's possible to use vga16fb (not vgacon) with "qemu-system-ppc -M pegasos2 -vga std" if that still boots at all. Support for pegasos2 hardware appears to have been removed with commit 04debf21fa174 ("powerpc: Remove core support for Marvell mv64x60 hostbridges"), but it's possible that this did not break qemu support if that only uses devices under arch/powerpc/platforms/chrp/pci.c. I could not get it to boot, but did not try very hard. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 30942C0015E for ; Fri, 21 Jul 2023 08:27:27 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7F77E10E631; Fri, 21 Jul 2023 08:27:26 +0000 (UTC) Received: from new3-smtp.messagingengine.com (new3-smtp.messagingengine.com [66.111.4.229]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8B14910E631 for ; Fri, 21 Jul 2023 08:27:24 +0000 (UTC) Received: from compute6.internal (compute6.nyi.internal [10.202.2.47]) by mailnew.nyi.internal (Postfix) with ESMTP id CDE4D58026A; Fri, 21 Jul 2023 04:27:21 -0400 (EDT) Received: from imap51 ([10.202.2.101]) by compute6.internal (MEProxy); Fri, 21 Jul 2023 04:27:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arndb.de; h=cc :cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm2; t=1689928041; x=1689935241; bh=V8 kkxioRFPjR/pcGqI7bYcicee1af9QaKC3pDwPABSg=; b=b9mWPVKTa+C0qxGJVm gVTKr5SnuCufxByEgtuEiTC/HjonV9yPvhgncSRQ0wUrLNE7orD78Rw7ohjT0q3C c0X7wLA5W1uO4gHBmiwybGJLQQ7SrEMtBGvFZKQaT/Y0wzIbtxoIfYUgm9pO+XSJ 6I08Fx8oDJAOPBCXHuGFZFeWb1RYZSXq09xFAfH85OnLe5l+htjQL+F/B4Y6gUvs ut/AOfdKRpwcHg/s2ox2GO/l5Ce/RBfBcnmaRO/F69sTDvSKTTvAQwHRFh24O6bw V6xDq+6cg4uZot5gbimNNmCu9SHpdf5MFTDtGh/g5OFBKMn02cs7TznQk+C9/i4Y dRwg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; t=1689928041; x=1689935241; bh=V8kkxioRFPjR/ pcGqI7bYcicee1af9QaKC3pDwPABSg=; b=unYn7VUfp/o2gT07nbqvQ5lIW9kBd mBnKota720DDPc/oG1aRttW/D+crNdOAUEl9St9nonOTjtR5EHZ/ERbVU6RS/8a9 h60zyLUrHFHJTeNLWeadDvND/TVlwE64W4ER4jaFI7yfcqQcM9JFFXLEQa8gKTAm 2NneyWtfI14HUK6C7gElYEN39Z+C3ZEMkQn2ZM6gax2xS8UlImkh100FKtZaGPhv lQk5OR6Mr17MQHWJ9UIPy7fklXcZo7AkC1hU9D8FRcT0DoHGZ1ht5evHlxZxLnfx AEw3wiOX0qizHBpHqwTM2HVi93NRv6iA2yioBToovm3YnDAmy38mo5uCg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrhedvgddtudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpefofgggkfgjfhffhffvvefutgesthdtredtreertdenucfhrhhomhepfdetrhhn ugcuuegvrhhgmhgrnhhnfdcuoegrrhhnugesrghrnhgusgdruggvqeenucggtffrrghtth gvrhhnpeffheeugeetiefhgeethfejgfdtuefggeejleehjeeutefhfeeggefhkedtkeet ffenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegrrh hnugesrghrnhgusgdruggv X-ME-Proxy: Feedback-ID: i56a14606:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id AB365B60089; Fri, 21 Jul 2023 04:27:19 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-531-gfdfa13a06d-fm-20230703.001-gfdfa13a0 Mime-Version: 1.0 Message-Id: <19631e74-415e-4dcb-b79d-33dcf03d2dfc@app.fastmail.com> In-Reply-To: <87pm4lj1w3.fsf@mail.lhotse> References: <20230719123944.3438363-1-arnd@kernel.org> <20230719123944.3438363-2-arnd@kernel.org> <87pm4lj1w3.fsf@mail.lhotse> Date: Fri, 21 Jul 2023 10:26:30 +0200 From: "Arnd Bergmann" To: "Michael Ellerman" , "Arnd Bergmann" , linux-fbdev@vger.kernel.org, "Thomas Zimmermann" , "Helge Deller" , "Javier Martinez Canillas" Subject: Re: [PATCH v2 1/9] vgacon: rework Kconfig dependencies Content-Type: text/plain X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-hyperv@vger.kernel.org, x86@kernel.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Catalin Marinas , Dave Hansen , dri-devel@lists.freedesktop.org, linux-mips@vger.kernel.org, Max Filippov , linux-efi@vger.kernel.org, guoren , "linux-csky@vger.kernel.org" , sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, WANG Xuerui , "K. Y. Srinivasan" , Ard Biesheuvel , Wei Liu , Will Deacon , Huacai Chen , Dexuan Cui , Russell King , Christophe Leroy , Deepak Rawat , Ingo Molnar , Matt Turner , Haiyang Zhang , Nicholas Piggin , Borislav Petkov , loongarch@lists.linux.dev, John Paul Adrian Glaubitz , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Khalid Aziz , Brian Cain , Thomas Bogendoerfer , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Dinh Nguyen , linux-riscv@lists.infradead.org, Palmer Dabbelt , linux-alpha@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "David S . Miller" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, Jul 21, 2023, at 06:59, Michael Ellerman wrote: > Arnd Bergmann writes: >> From: Arnd Bergmann >> >> The list of dependencies here is phrased as an opt-out, but this is missing >> a lot of architectures that don't actually support VGA consoles, and some >> of the entries are stale: >> >> - powerpc used to support VGA consoles in the old arch/ppc codebase, but >> the merged arch/powerpc never did > > Not disputing this, but how did you come to that conclusion? I grepped > around and couldn't convince myself whether it can work on powerpc or > not. ie. currently it's possible to enable CONFIG_VGA_CONSOLE and > powerpc does have a struct screen_info defined which seems like it would > allow vgacon_startup() to complete. The VGA console needs both screen_info and vga_con to work. In arch/ppc we had both, but in arch/powerpc we only retained the screen_info: $ git grep vga_con v2.6.26 -- arch/ppc arch/ppc64 arch/powerpc v2.6.26:arch/ppc/platforms/pplus.c: conswitchp = &vga_con; v2.6.26:arch/ppc/platforms/prep_setup.c: conswitchp = &vga_con; so after arch/ppc was removed, this became impossible to use on both pplus and prep. These two platforms were also (as far as I can tell) the only ones to support vga16fb as an alternative to vgacon, but both platforms were removed later on. > My only concern is that someone could be using it with Qemu? I have not yet ruled out anyone using vga16fb on qemu before commit 0db5b61e0dc07 ("fbdev/vga16fb: Create EGA/VGA devices in sysfb code"), but I can see that this has been broken for 12 months without anyone complaining about it, since vga16fb no longer works with the "orig_video_isVGA == 1" setting in arch/powerpc (the device is not created). In the qemu sources, I see five powerpc machines that intialize VGA support: mac_newworld, mac_oldworld, pegasos2, prep, and spapr. I think we can exclude prep (which was removed from the kernel) and spapr (64-bit VGA_MAP_MEM() looks broken). I think the macs always come up in graphical mode and only use offb/atifb/rivafb/matroxfb but not vga16fb that would require running the x86 VGA BIOS initialization. I suppose it's possible to use vga16fb (not vgacon) with "qemu-system-ppc -M pegasos2 -vga std" if that still boots at all. Support for pegasos2 hardware appears to have been removed with commit 04debf21fa174 ("powerpc: Remove core support for Marvell mv64x60 hostbridges"), but it's possible that this did not break qemu support if that only uses devices under arch/powerpc/platforms/chrp/pci.c. I could not get it to boot, but did not try very hard. Arnd