This reverts commit ba806f98f868ce107aa9c453fef751de9980e4af. Disabling AGP leaves some hardware without working alternative on some platforms. For example, PCI GPUs are known to be broken on K8 and K10 platforms since years: the breakage was reproduced from Linux 4.4 on Ubuntu 16.04 Xenial to Linux 5.10-rc1 on Ubuntu 20.04 Focal, and it is expected to be older than Linux 4.4.
Also, there may be some bugs specific to AGP GPUs being driven as PCI ones since fixing some PCI bugs introduces newer bugs that are very specific to AGP GPUs driven as PCI ones and not to PCI native ones. Some AGP GPUs are still relevant to this day, like the high-end ATI Radeon HD 4670 AGP (RV730 XT), a very capable TeraScale GPU designed for OpenGL 3.3 and OpenCL 1.0 and featuring HDMI port and 1GB of VRAM. This GPU was distributed by various manufacturers and was still sold as brand new in 2012, for example this one: http://www.hisdigital.com/un/product2-448.shtml https://web.archive.org/web/2012/https://www.amazon.com/gp/product/B003CYKCG8/ As an example, this AGP GPU still gets 140+ fps on the competitive Xonotic game in 2020, as verified during the XDWC 2020 event, also when compared to other games on the Unvanquished GPU compatibility matrix, we can notice that to outperform such GPU, Intel users have to acquire an UHD 600 graphic chip from 2016, and Nvidia users relying on the free open source nouveau driver have to acquire a GTX 1060 from 2016: https://wiki.unvanquished.net/wiki/GPU_compatibility_matrix Motherboards compatible with powerful CPUs like the quad core AMD AM3 Phenom II CPU X4 970 (3.5GHz) supporting virtualization, 16GB of RAM and featuring AGP and PCI slots (not PCI Express ones) were sold, like this motherboard from 2006 supporting this CPU from 2010: https://www.asrock.com/mb/nvidia/am2nf3-vsta/ https://www.cpu-world.com/cgi-bin/IdentifyPart.pl?PART=HDZ970FBK4DGM This is basically among the best the market had to offer in 2012 for AGP users. Disabling AGP turns such very capable computers and their AGP GPUs into paperweights. Even if PCI and AGP-as-PCI issues are fixed, disabling AGP is expected to strongly affect performance of such GPUs, and disabling AGP may hide bugs that may be introduced after the disablement. A boot command line switch to disable AGP to rely on PCI fallback may be welcome to help testing the PCI code and prevent it to rot as it is easier to find AGP cards than PCI ones. See related bugs: - https://bugs.launchpad.net/bugs/1899304 (this one) > AGP disablement leaves GPUs without working alternative > (PCI fallback is broken), makes very-capable ATI TeraScale GPUs > unusable - https://bugs.launchpad.net/bugs/1902981 > AGP GPUs driven as PCI ones (when AGP is disabled at kernel build > time) are known to fail on K8 and K10 platforms - https://bugs.launchpad.net/bugs/1902795 > PCI graphics broken on AMD K8/K10 platform (while it works on Intel) > verified from Linux 4.4 to 5.10-rc1 ** Patch added: "PATCH: Revert ba806f9 "drm/radeon: disable AGP by default"" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1899304/+attachment/5431457/+files/0001-Revert-drm-radeon-disable-AGP-by-default.patch -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1899304 Title: AGP disablement leaves GPUs without working alternative (PCI fallback is broken), makes very-capable ATI TeraScale GPUs unusable Status in linux package in Ubuntu: Confirmed Bug description: This system runs Ubuntu 20.04, freshly installed 3~4 months ago (July 2020). There is two kernels available on this system: - 5.4.0-47-generic - 5.4.0-48-generic With kernel 5.4.0-47-generic: - GNOME shell loads properly on Radeon X1950 PRO, - Unvanquished game runs on ATI Radeon X1950 PRO at 70 fps on 1280×720 resolution, - Unvanquished game runs on ATI Radeon 9500 at 40 fps on 640×480 resolution. Everything looks consistent with the limits and the age of the hardware. With kernel 5.4.0-48-generic: - GNOME Shell never finish to load on Radeon X1950 PRO, either a grey screen is displayed and keyboard shortcuts does not respond, or the top bar is stuck between the center and the top of the screen and the shell does not respond, or the top bar on the top of the screen but the shell does not respond, to get a desktop I run `sudo systemctl stop display-manager` then `startx /usr/bin/lxsession` from a TTY. Running GNOME Shell with startx or from a lone xterm started with startx leads to same issues. - Unvanquished game runs on ATI Radeon X1950 PRO at 7 fps on 1280×720 resolution, - Unvanquished game runs on ATI Radeon 9500 at 3 fps on 640×480 resolution. Note: for unknown reasons, GNOME Shell loads properly on the ATI Radeon 9500 but not on the Radeon X1950 PRO. Everything is slow. When the game is running, a very high load is reported by htop, which does not look like the experience seen on the 5.4.0-47-generic kernel. When the game is running cycling between windows using Alt-Tab takes a lot of second while it's immediate on 5.4.0-47-generic kernel. Also, even without the game running or on a lightweight desktop like LXDE, cycling windows is not smooth and window refreshing is slow enough to be noticeable. About the hardware, note that: - the CPU only has one core, no hyperthreading (AMD Athlon 64 FX for socket 939), - the GPUs are AGP ones using R300 and R500 technology (pre-TeraScale), - there is 3GB of DDR RAM, - there is no on-disk swap but zram-based swap in compressed ram is used, - system is stored on and boots from an USB 3.1 key plugged on an USB 2.0 port, - /tmp is a tmpfs ram disk, - CPU is set to performance profile, - the install is not really messy and not many packages are installed, this USB key is purposed for hardware/system testing and to diagnose such issues. ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-48-generic 5.4.0-48.52 ProcVersionSignature: Ubuntu 5.4.0-48.52-generic 5.4.60 Uname: Linux 5.4.0-48-generic x86_64 ApportVersion: 2.20.11-0ubuntu27.9 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: illwieckz 7503 F.... pulseaudio CasperMD5CheckResult: skip Date: Sun Oct 11 01:47:48 2020 InstallationDate: Installed on 2020-07-09 (93 days ago) InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423) IwConfig: enp0s11 no wireless extensions. lo no wireless extensions. MachineType: MSI MS-6702E ProcEnviron: TERM=xterm-256color PATH=(custom, no user) LANG=fr_FR.UTF-8 SHELL=/bin/bash ProcFB: 0 radeondrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-48-generic root=UUID=10314d0c-ec6b-4f7f-b926-ed8b80185331 ro PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. RelatedPackageVersions: linux-restricted-modules-5.4.0-48-generic N/A linux-backports-modules-5.4.0-48-generic N/A linux-firmware 1.187.3 RfKill: SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 10/12/2006 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 080011 dmi.board.asset.tag: To Be Filled By O.E.M. dmi.board.name: MS-6702E dmi.board.vendor: MSI dmi.board.version: 1.0 dmi.chassis.asset.tag: To Be Filled By O.E.M. dmi.chassis.type: 3 dmi.chassis.vendor: To Be Filled By O.E.M. dmi.chassis.version: To Be Filled By O.E.M. dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr080011:bd10/12/2006:svnMSI:pnMS-6702E:pvr1.0:rvnMSI:rnMS-6702E:rvr1.0:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.: dmi.product.family: To Be Filled By O.E.M. dmi.product.name: MS-6702E dmi.product.sku: To Be Filled By O.E.M. dmi.product.version: 1.0 dmi.sys.vendor: MSI To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1899304/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
