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

[Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Sun, 18 Feb 2018 23:15:32 +0100
Yves-Alexis Perez <corsac-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org> wrote:

> On Tue, 2018-02-13 at 13:40 -0800, Raj, Ashok wrote:
> > This version has only hw dumps for now, but we plan to add some
> > other things like walking 2nd level page-tables, or get some SVM
> > specific data from the driver in the future.   
> 
> Hi,
> 
> I'm not sure how much you know about chipsec [1], but with a oneliner
> [2] you can have it print a lot of data from Vt-d configuration,
> including page tables. As far as I remember, it doesn't need access
> to /dev/mem (but I gidn't dig to check how it does it).
> 
> It might still be useful to have everything from debugfs because
> it'll always be consistent with the current running kernel, but at
> least it might help users reporting bugs.
> 
> [1] https://github.com/chipsec/chipsec
> [2] http://paste.debian.net/1010105

I didn't know about chipsec but reading the code seems to rely on an
out-of-tree kernel module. I don't think it matches what we need here.