Re: [gentoo-user] Issues with AMD_IOMMU

[Corbin Bird]

On 05/14/2017 12:31 AM, Adam Carter wrote:
> Tried kernels 4.10.13 and 4.11, with
> CONFIG_GART_IOMMU=y
> CONFIG_IOMMU_HELPER=y
> CONFIG_IOMMU_API=y
> CONFIG_IOMMU_SUPPORT=y
> CONFIG_IOMMU_IOVA=y
> CONFIG_AMD_IOMMU=y
> CONFIG_AMD_IOMMU_V2=m
> Chipset is 990FX, and AFAICT the V2 is for the APU (bdver3 and 4 vintage).
>
> When I enable the IOMMU in the BIOS I get stack traces. Is anyone using
> AMD_IOMMU successfully? If so, any tips?

-----

Background / System Info : 2 systems.
Chipset 990FX, FX-9590 ( -march=bdver2 / Fam15h )
Chipset 790FX, PhenomII 980 ( -march=amdfam10 / Fam10h )
Gentoo x86_64, multilib, Kernel 4.9.x
IOMMU enabled in UEFI, BIOS.

-----


General Info : ( if you don't know already ... )

The 990FX / 790FX Chipset doesn't have a GART / AGP Aperature or IOMMU
in it.
The CPU contains the original K8 IOMMU ( v1 ) engineered / converted
from a GART.

Standard output in '/var/log/dmesg'.

> [    0.000000] AGP: No AGP bridge found

> [    0.926911] PCI-DMA: Disabling AGP.
> [    0.927142] PCI-DMA: aperture base @ b4000000 size 65536 KB
> [    0.927263] PCI-DMA: using GART IOMMU.
> [    0.927376] PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture

-----

Suggestion :

read the Kernel Parameter docs. The automatic setup may need tweaking.

You have to do a manual setup if you want, both, a working IOMMU and an
AGP Aperature. Firmware can throw a major monkey wrench into that type
of setup however.

> /usr/src/linux/Documentation/kernel-parameters.txt

This doc has the x86_64 IOMMU options listed ...
> /usr/src/linux/Documentation/x86/x86_64/boot-options.txt


Question :

APU?
I was under the impression that those CPU's used a different chipset,
not the 990FX.


Corbin