Comment 35 for bug 1776563

Hi AaronMa,

thanks for the response. I tried it but it didn't work. I think iommu problem is not the main reason of the kernel hang. Otherwise it can be disabled in BIOS and there is no change.

The main reason is: like you can se on this picture is that IOAPIC[4] and IOAPIC[5] are not in the invrs table so we should search the correct pci controllers using lspci and give them to the kernel.

In this way:
LINUX_DEFAULT="quiet splash ivrs_ioapic[4]=00:14.0 ivrs_ioapic[5]=00:00.2"

Kernel can be started even with noapic but two sensors will be missing and the advanced touchpad functions will not work. This is the reason of CONFIG_VGA_SWITCHEROO=n compile time kernel parameter.

There is an another problem: this notebook has two GPUs and amdgpu (or the kernel, I don't know) can not handle this correctly so gpu switching has to be disabled