4

I've got new laptop at work (Lenovo A485) and there are few issues with it. It prints AMD-Vi: IOAPIC[32] not in IVRS table and kernel panic after that. So far I've figured few ways to get the system up and running.

  • noapic - terrible performance and high temperature, so not really a good way to do it
  • amd_iommu=off - not ideal either
  • ivrs_ioapic[32]=00:14.0 ivrs_ioapic[33]=00:00.2 - this seems to work fine
  • iommu=soft

My questions are about iommu=soft. I'm not sure what exactly it does. What are the implications of this mode? What is preferable, overriding the IVRS table or iommu=soft?

3

iommu==soft tells the kernel to use a software implementation to remap memory for applications that can't read above the 4GB limit.

The kernel documentation for these options is here: https://github.com/spotify/linux/blob/master/Documentation/x86/x86_64/boot-options.txt#L207

What's preferable is a solution that satisfies your expectations for performance, system temperature, battery life, etc, etc. If iommu=soft give you satisfactory performance, temperature, and battery life, then I would say go with that.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.