linux-kernel - Re: [PATCH v2] iommu/vt-d: Dump DMAR translation structure

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Message-ID: <43dbe366ef396a81357c032ea62d8b9543678a3d.camel@intel.com>
Date:   Fri, 30 Jul 2021 16:51:02 -0700
From:   Kyung Min Park <kyung.min.park@...el.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        baolu.lu@...ux.intel.com, dwmw2@...radead.org, will@...nel.org,
        yian.chen@...el.com, sohil.mehta@...el.com,
        ravi.v.shankar@...el.com, ashok.raj@...el.com
Subject: Re: [PATCH v2] iommu/vt-d: Dump DMAR translation structure

Hi Joerg,

On Mon, 2021-07-26 at 14:25 +0200, Joerg Roedel wrote:
> On Wed, Jul 21, 2021 at 09:24:53PM -0700, Kyung Min Park wrote:
> > When the dmar translation fault happens, the kernel prints a single
> > line
> > fault reason with corresponding hexadecimal code defined in the
> > Intel VT-d
> > specification.
> > 
> > Currently, when user wants to debug the translation fault in
> > detail,
> > debugfs is used for dumping the dmar_translation_struct, which is
> > not
> > available when the kernel failed to boot.
> > 
> > Dump the DMAR translation structure, pagewalk the IO page table and
> > print
> > the page table entry when the fault happens.
> > 
> > Signed-off-by: Kyung Min Park <kyung.min.park@...el.com>
> 
> This is too much noise in dmesg for a single dmar fault. Please hide
> that additional debug information behind a debug kernel option for
> the
> VT-d driver.

Sure, let me change in the next version.