There are so many bits, so little time. I have utterly forgotten how vt-d gets enabled.
Anyway, there's two bits and a lock bit. coreboot very deliberately does nothing with any of them -- this was a design decision a few years ago -- and it leaves them in a state that you can control them. So the 'enable vt-x' part is easy and kvm will do it for you when you load the module, or you can do it with the wrmsr command (for each core! -- if you only do one core it will go badly).
ron
On Sun, Jul 26, 2015 at 3:40 AM Noah Vesely fowlslegs@riseup.net wrote:
Thanks Ron! Took bit to get back to you because a Xen hypervisor update in Qubes seemed to put me in a boot loop. I just installed an Arch derivative because Arch has good support for this machine and I needed some type of test environment to actually run this command.
Anyway, `rdmsr 0x3a` (think this is what you meant to type) returns 0. I guess this means all 3 bits are not set in the IA32_FEATURE_CONTROL MSR.
This doesn't immediately make sense to me because (1) the output here seems to be telling me VT-x is not activated and the vmx cpu flag is present =><= and (2) I wrote in because `xl info` in Xen was reporting VT-x, but not VT-d, was activated and I was interested in how I could activate the former--isn't 0x3a unrelated to VT-d? Hopefully you can clarify this for me.
Noah
On 07/24/2015 11:25 PM, ron minnich wrote:
what does rdmsr 0 0x3a show you?
ron
On Fri, Jul 24, 2015 at 10:06 PM Noah Vesely fowlslegs@riseup.net
wrote:
I've been trying to get VT-d working on John Lewis's build for the 2015 Pixel (samus). You can see our conversation at https://plus.google.com/116173342884039282107/posts/TGA4EXYQMfq and I have also pasted it below. So far, I haven't got anywhere, so I thought I would try asking you all as well.
Thanks, Noah
&%$#&%$#&%$#&%$#&%$#&%$#&%$#&%$#&%$#
Noah Vesely
- Jul 16, 2015
Is it possible to get Intel VT-d working on the Chromebook Pixel 2/ Samus? The i7-5600U processor does support it. ARK | Intel® Core™ i7-5600U Processor (4M Cache, up to 3.20 GHz) ark.intel.com ARK | Intel® Core™ i7-5600U Processor (4M Cache, up to 3.20 GHz) quick reference guide including specifications, features, pricing, compatibility, design documentation, ordering codes, spec codes and
more.
John Lewis's profile photoNoah Vesely's profile photo 10 comments John Lewis Jul 18, 2015
AFAIK, none of the hardware VT extensions are disabled in the firmware on Samus. Have you tried it? Noah Vesely Jul 18, 2015
Yes. VT-x was enable while VT-d was not. John Lewis Jul 18, 2015
Clone
https://chromium.googlesource.com/chromiumos/third_party/coreboot/+/firmware...
and run menuconfig to see if there's an option for VT-d. Noah Vesely Jul 19, 2015
I can't figure out how to checkout this repository. I cloned the main third_part/coreboot repo then checked out the broadwell branch, but could not find the same directory you linked. Maybe my git fu could use some work. John Lewis Jul 20, 2015
Use the last chunk of the URL as the branch argument i.e. "-b firmware-samus-6300.B". Noah Vesely Jul 20, 2015
Nothing in menuconfig, however, I found the line `#define CONFIG_IOMMU 0` in ./build/config.h. I also found `#define CONFIG_ENABLE_VMX 0`. John Lewis Jul 21, 2015
VMX is already enabled in the firmware. IOMMU is unrelated. I would have to conclude that VT'd is either not supported by that CPU or something more needs to be done in coreboot to get it to work. Noah Vesely Jul 21, 2015
VT-d is supported by this CPU. See original link to Intel Ark.
VT-d is Intel's specification for their IOMMU technology, so I don't see how it's unrelated. John Lewis Jul 21, 2015
Take a look at the .config from a shellball ROM (you can extract it using cbfstool).
https://johnlewis.ie/extracting-the-shell-ball-rom-using-a-chromeos-image/
Noah Vesely 9:15 PM
I don't see anything relevant to VT-d; no VT-d keywords (e.g., iommu, vt, vmx, hvm, and directio).
http://paste.debian.net/hidden/08ac8494/%EF%BB%BF
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