Hi,
On 2023/8/3 20:25, kernel test robot wrote:
Hi Sui,
kernel test robot noticed the following build errors:
[auto build test ERROR on pci/next]
[also build test ERROR on pci/for-linus linus/master v6.5-rc4 next-20230803]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Sui-Jingfeng/PCI-VGA-Make-the-vga_is_firmware_default-arch-independent/20230803-161838
base: https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git next
patch link: https://lore.kernel.org/r/20230803081758.968742-1-suijingfeng%40loongson.cn
patch subject: [PATCH] PCI/VGA: Make the vga_is_firmware_default() arch-independent
config: arm64-randconfig-r026-20230731 (https://download.01.org/0day-ci/archive/20230803/202308032022.yiZngbbk-lkp@xxxxxxxxx/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce: (https://download.01.org/0day-ci/archive/20230803/202308032022.yiZngbbk-lkp@xxxxxxxxx/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308032022.yiZngbbk-lkp@xxxxxxxxx/
All errors (new ones prefixed by >>):
ld.lld: error: undefined symbol: screen_info
>>> referenced by vgaarb.c:86 (drivers/pci/vgaarb.c:86)
>>> drivers/pci/vgaarb.o:(vga_arb_firmware_fb_addr_tracker) in archive vmlinux.a
>>> referenced by vgaarb.c:86 (drivers/pci/vgaarb.c:86)
>>> drivers/pci/vgaarb.o:(vga_arb_firmware_fb_addr_tracker) in archive vmlinux.a
>>> referenced by vgaarb.c:88 (drivers/pci/vgaarb.c:88)
>>> drivers/pci/vgaarb.o:(vga_arb_firmware_fb_addr_tracker) in archive vmlinux.a
>>> referenced 3 more times
This is a more like arch-specific problem, It will be pain at many places on platforms
that do not export the screen_info symbol. Not only here.
I have already explained that screen_info is arch-dependent many times, but no one cares about me.
By using (looking at) screen_info, vgaarb gets infected, and becomes arch-dependent as well.
vgaarb deals with VGA class (pdev->class == 0x0300XX) devices only, This makes it device-dependent.
Hence, It only works correctly for a small set of PCIe devices on x86.
arch-dependent, device-dependent, subsystem-dependent (part of it rely on ACPI) and
loading order dependent, those dependent itself are the problems.
It results in various undefined (uncertain) behaviors on non-x86 architectures.
Even on x86, some platform choose to relay on the firmware to solve the multiple GPU coexist problem.
so it is also firmware-dependent.
This patch solves part of the above problems listed, target at the *device level*, as early as possible.
while they still a few problems could be only solved at the *driver level*.
For an example, The display controller in Intel N2000 and d2000 series don't has a dedicated VRAM bar.
they use the "stolen memory", which is carve out by somebody (either bios or kernel?).
