Re: [RFC v6][PATCH 4/4] intel_txt: force IOMMU on for Intel(R) TXT launch

[Ingo Molnar <mingo@elte.hu>]

* Pavel Machek <pavel@ucw.cz> wrote:

> 
> On Tue 2009-06-30 19:31:10, Joseph Cihula wrote:
> > The tboot module will DMA protect all of memory in order to ensure the that
> > kernel will be able to initialize without compromise (from DMA).  Consequently,
> > the kernel must enable Intel(R) Virtualization Technology for Directed I/O
> > (VT-d or Intel IOMMU) in order to replace this broad protection with the
> > appropriate page-granular protection.  Otherwise DMA devices will be unable
> > to read or write from memory and the kernel will eventually panic.
> > 
> > Because runtime IOMMU support is configurable by command line options, this
> > patch will force it to be enabled regardless of the options specified, and will
> > log a message if it was required to force it on.
> > 
> > 
> >  dmar.c        |    7 +++++++
> >  intel-iommu.c |   17 +++++++++++++++--
> >  2 files changed, 22 insertions(+), 2 deletions(-)
> > 
> > Signed-off-by: Joseph Cihula <joseph.cihula@intel.com>
> > Signed-off-by: Shane Wang <shane.wang@intel.com>
> 
> NAK. Breaks user expectations, misses  docs updates. 

What's your proposed solution? If an incompatible IOMMU option is 
specified should the kernel to disable TXT and panic?

	Ingo