[coreboot] VT-d on Pixel 2015 (samus)

[Noah Vesely]

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 at 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-samus-6300.B
>> 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/
>>
>> --
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