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.
The DMAR requirements are not met on all platforms. But even after boot you can insert DMAR tables into kernels.
So there is a key distinction between required support and desired support, and I wonder if you could figure out what is required and let us know what it is.
BTW, Do we have core boot tested on Intel’s Atom based C3xxx family SoCs?
On Mon, Jun 5, 2017 at 9:39 AM Zoran Stojsavljevic zoran.stojsavljevic@gmail.com wrote:
what support does it need?
Intel Virtualization Technology for Directed I/O" (VT-d). VT-d is a virtualized IOMMU, so by using HYP type 1 there should be a VT-d driver supporting VT-d HW extension (?), as my best understanding is
The practical implications are Graphics and Network Connectivity in Guests. DMA Remapping is the feature of VT-d.
Good net pointer to read: https://unix.stackexchange.com/questions/34428/do-virtualbox-or-vmware-use-t...
Is anybody working on this?
Don't think so... If anything is done, I guess, it is done by simplistic implementation of the feature called: pass-through (so guest by its own drivers is using directly platform devices' HW bypassing HYP1, my best guess).
Zoran On Mon, Jun 5, 2017 at 6:11 PM, ron minnich rminnich@gmail.com wrote:
On Mon, Jun 5, 2017 at 9:00 AM Himanshu Chauhan hschauhan@nulltrace.org wrote: Hi,
VT-d requires support from BIOS. Does coreboot support VT-d?
what support does it need?
-- coreboot mailing list: coreboot@coreboot.org https://mail.coreboot.org/mailman/listinfo/coreboot
On Mon, Jun 5, 2017 at 9:58 AM Himanshu Chauhan hschauhan@nulltrace.org wrote:
I think its can’t just be disabled.
oh, really? Why do you think that? Have you looked at the relevant MSR and what is the basis of your claim?
ron
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
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
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Himanshu Chauhan -
Nico Huber -
ron minnich -
Zoran Stojsavljevic