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 code)?!
Zoran
On Mon, Jun 5, 2017 at 7:34 PM, Nico Huber nico.h@gmx.de wrote:
Hi,
On 05.06.2017 18:58, Himanshu Chauhan wrote:
On 05-Jun-2017, at 10:19 PM, ron minnich rminnich@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