Hi, On 05.06.2017 18:58, Himanshu Chauhan wrote: > >> On 05-Jun-2017, at 10:19 PM, ron minnich <[email protected]> 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 -- coreboot mailing list: [email protected] https://mail.coreboot.org/mailman/listinfo/coreboot
