[coreboot] VT-d support

Zoran Stojsavljevic zoran.stojsavljevic at gmail.com
Mon Jun 5 19:47:43 CEST 2017

> If you are lucky, you only need to add 20~30 lines to your chipset's code.

Could you, please, show us an explicit example (of these 20 to 30 lines of


On Mon, Jun 5, 2017 at 7:34 PM, Nico Huber <nico.h at gmx.de> wrote:

> Hi,
> On 05.06.2017 18:58, Himanshu Chauhan wrote:
> >
> >> On 05-Jun-2017, at 10:19 PM, ron minnich <rminnich at gmail.com> wrote:
> >>
> >> The reason I ask about what you need is that on chromebooks the main
> >> coreboot support came down to 'don't disable anything’.
> >
> > I think its can’t just be disabled. Its just that kernel is not given
> > any knowledge about its existence. This is what I want to know. The
> > commercial BIOSes give an option of “enable VT-d” support. What do they
> > do when this option is selected? Can this be implemented in Coreboot?
> > This probably brings me to your next question of what is required. I
> > would spend some time to figure that out.
> First thing, the firmware doesn't have to support it. It's only that
> Intel chose _not_ to write per platform OS drivers and let the firm-
> ware do the abstraction instead (I know a kernel that works pretty well
> with VT-d even if there are no DMAR tables).
> coreboot already handles VT-d support on some chipsets (GM45, Sandy/
> Ivy Bridge come to mind). You can look how it's done there. If you are
> lucky, you only need to add 20~30 lines to your chipset's code.
> If your chipset needs special initialization, it's most probably docu-
> mented in the BIOS Writer's Guide (BWG) or BIOS Specification. Though,
> you need an NDA with Intel to get these.
> Nico
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