Re: [PATCH v3 0/8] Introduce debugfs support in IOMMU

Suthikulpanit, Suravee
2025-02-06T08:56:28Z

On 2/6/2025 12:59 PM, Dheeraj Kumar Srivastava wrote:
> From: root <root@BLRDHSRIVAS.amd.com>
>
> Introducing debugfs support in AMD/IOMMU driver that will allow
> userspace to dump below IOMMU information
> 1) MMIO and Capability register per IOMMU
> 2) Command buffer
> 3) Device table entry
> 4) Interrupt remapping table entry
>
> Analyzing contents of IOMMU data structures helps in understanding IOMMU
> capabilities and behavior and debug issues faster.
>
> 1. MMIO and Capability registers - Add support to dump MMIO and Capability
> registers per IOMMU.
>
> Example:
> a. Write MMIO register offset to dump it
> $ echo 0x18 > /sys/kernel/debug/iommu/amd/iommu00/mmio
> $ cat /sys/kernel/debug/iommu/amd/iommu00/mmio
>
> Output:
> $ 0x0003f48d

Correction: Based on the documentation in patch 8/8, the output would be

Offset:0x18 Value:0x0003f48d

> b. Write capability register offset to dump it
> $ echo 0x10 > /sys/kernel/debug/iommu/amd/iommu00/capability
> $ cat /sys/kernel/debug/iommu/amd/iommu00/capability
>
> Output:
> $ 0x00203040

Correction: Based on the documentation in patch 8/8, the output would be

Offset:0x10 Value:0x00203040

Suravee