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 35FAA2737FE for ; Tue, 1 Jul 2025 18:28:28 +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=1751394511; cv=none; b=I9/9gRr713pNy5fKGIm+w2WkQWXUbByRLBj2Sr/qQI1lMl+KDE76JPIiSZ6iK/zkPwKlkz8+jB0z1C035iwXjdMFmDipAwmWrlabVE9QS1vjhCQduyBqRVZ1sO1zThfjj2yTcs8lwJQEkHh6N+twioypDSkKHquaHaaYskYeP+Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751394511; c=relaxed/simple; bh=LuTX3P4IYw+u/KYDxEgQkZlp5bfr+R16L5KEBJ2dFeM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZigdZizGuUXyiEIhVz+jA1/lQhdrlLDV4tKPSl1SxCSSTNVFFx+xaJkmOKf9kWVc/XVPnlL0jHaxkhMb3+kZ80M+st99lYfaAHyFUbfgT9BRpg8B4UczTh7jnucQrBltSsRn2EfMOblkISgimiNarxYsil9NcwajN2qR7eMUSV0= 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 6BD232C06643; Tue, 1 Jul 2025 20:28:26 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 5A77A3A083B; Tue, 1 Jul 2025 20:28:26 +0200 (CEST) Date: Tue, 1 Jul 2025 20:28:26 +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. I agree that probing *any* PCI device should never have been introduced, much less made the default. But changing that risks regressing users that depend on it. The conservative approach is to retain the existing behavior, but make it more benign by constraining probing to devices with AGP Capability, as we did prior to 6fd024893911. Thanks, Lukas