From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bmailout1.hostsharing.net (bmailout1.hostsharing.net [83.223.95.100]) (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 F1D912E03E8 for ; Wed, 2 Jul 2025 15:24:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=83.223.95.100 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751469851; cv=none; b=jef22rqWOAWnVxa0cwDxdPUhMn/XqDEsYNBgJizAUww7I9DXXhBN+fOhGjoaNVUWN55GYDmMicO0uxIpwku2h68DdnjmrRJKGZInsqgVjDXuBfrjSVLvkEv1fS8v6rDgKYEFcyPkXA0VzOXG2QEb/M79Qt3c2K/5A7vYiHhtKVU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751469851; c=relaxed/simple; bh=REQJvMOxPN1zceDMB+5oPsUix0Ymins0V8euAwSCMcE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ooCONp42GjFqaD9LXK3dAntTNoAoEbFHHp1TNXxK/5XqdPpYNzbiHhJXpkJjIUMtsLsO54oYa2lS4Z+zBhivr3EjXtKb/3cppvOS+A9D2mKx1LtHH3SLnDorvijgdJ8dReKxS3f7+HZFBXEpduZt5hjkYoOL7ogpZLRbEYCWGV8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de; spf=none smtp.mailfrom=h08.hostsharing.net; arc=none smtp.client-ip=83.223.95.100 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=h08.hostsharing.net Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "*.hostsharing.net", Issuer "RapidSSL TLS RSA CA G1" (verified OK)) by bmailout1.hostsharing.net (Postfix) with ESMTPS id E67242C06841; Wed, 2 Jul 2025 17:24:06 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id CEC83402D97; Wed, 2 Jul 2025 17:24:06 +0200 (CEST) Date: Wed, 2 Jul 2025 17:24:06 +0200 From: Lukas Wunner To: Hans de Goede Cc: Ben Hutchings , David Airlie , Bjorn Helgaas , Joerg Roedel , Suravee Suthikulpanit , Andi Kleen , Ahmed Salem , Borislav Petkov , dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, linux-pci@vger.kernel.org Subject: Re: [PATCH] agp/amd64: Bind to unsupported devices only if AGP is present Message-ID: References: <279f63810875f2168c591aab0f30f8284d12fe02.camel@decadent.org.uk> <9077aab5304e1839786df9adb33c334d10c69397.camel@decadent.org.uk> <98012c55-1e0d-4c1b-b650-5bb189d78009@redhat.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Jun 25, 2025 at 08:43:45PM +0200, Hans de Goede wrote: > On 25-Jun-25 4:33 PM, Lukas Wunner wrote: > > So how do you know that all of these unsupported devices have > > PCI_CLASS_BRIDGE_HOST? > > The top of the driver says > > * This is a GART driver for the AMD Opteron/Athlon64 on-CPU northbridge. > * It also includes support for the AMD 8151 AGP bridge > > Note this only talks about north bridges. > > Also given the age of AGP, I would expect the agp_amd64_pci_table[] > to be pretty much complete and the need for probing for unknown AGP > capable bridges is likely a relic which can be disabled by default. > > Actually the amd64-agp code is weird in that has support for > unknown AGP bridges enabled by default in the first place. > > The global probe unknown AGP bridges bool which is called > agp_try_unsupported_boot is false by default. > > As discussed in the thread with my patch, we should probably > just change the AMD specific agp_try_unsupported to default > to false too. Since the breaking change (causing the annoying message) was introduced in this cycle, I think we should err on the side of caution and avoid the risk of creating new regressions, if at all possible. However if you are willing to deal with potential fallout, I would like to encourage you to set "agp_try_unsupported = 0" (which the Kconfig help text suggests is already the case) as a patch for the next cycle. If you could give v2 of my (just submitted) patch a spin and respond with a Tested-by on success, I'd be grateful. I think this could go in either through drm-misc-fixes or pci/for-linus (since the offending commit went in through the pci tree). Thanks! Lukas