Re: [PATCH v7 0/5] Add Intel IOMMU debugfs support

[Joerg Roedel]

On Fri, Feb 02, 2018 at 04:49:56PM -0800, Sohil Mehta wrote:
> This series aims to add debugfs support for Intel IOMMU. It exposes IOMMU
> registers, internal context and dumps individual table entries to help debug
> Intel IOMMUs.
> 
> The first patch does the ground work for the following patches by reorganizing
> some Intel IOMMU data structures. The following patches create a new Kconfig
> option - INTEL_IOMMU_DEBUG and add debugfs support for IOMMU context internals,
> register contents, PASID internals, and Interrupt remapping in that order. The
> information can be accessed in sysfs at '/sys/kernel/debug/intel_iommu/'.

This looks like it only presents data from the iommu-hardware (register
state) or from in-memory data structures used by the hardware. Can't all
this be read out from user-space with libpci and /dev/mem access?

Things are different for kernel-defined data structures, as they might
change between releases and can be presented to user-space via debugfs
is needed, but the data structures used by the hardware should be pretty
stable.


	Joerg