Re: [regression, bisected, pci/iommu] Bug 216865 - Black screen when amdgpu started during 6.2-rc1 boot with AMD IOMMU enabled

From: Matt Fagnani
Date: Tue Jan 10 2023 - 03:08:43 EST


Baolu,

I tried to apply your patch after checking out 6.2-rc3 and origin/master but there were there the following errors.

git apply amd-iommu-amdgpu-boot-crash-2.patch
error: patch failed: drivers/pci/ats.c:382
error: drivers/pci/ats.c: patch does not apply

I manually changed drivers/pci/ats.c as shown in the patch. I built 6.2-rc3 + the patch. 6.2-rc3 with the patch had the same black screen problem when booting. I added rd.driver.blacklist=amdgpu on the kernel command line to prevent amdgpu from being started while the initramfs was in use, and the black screen happened later in the boot as I described in my previous email. The journal showed the same two warnings and null pointer dereference which made amdgpu crash as I reported.

Thanks,

Matt