[vfio-users] Passing intel_iommu=on in grub causes boot to immediately lock on two different X58 LGA1366 MB.

[Alex Williamson]

On Tue, May 17, 2016 at 1:19 PM, Brian Yglesias <
brian at atlanticdigitalsolutions.com> wrote:

> The first is an Asus Rampage II Gene.  While the manual claims VT-d
> support, Asus boards are known to break PCI pass through in linux.  The CPU
> is a ci7 920.
>
> I went out and purchased a ga-ex58-ud5, partly because I'd heard reports
> of it working in Linux with a few different configuratio
>
> The first is an Asus Rampage II Gene.  While the manual claims VT-d
> support, Asus boards are known to break PCI pass through in linux.  The CPU
> is a ci7 920.
>
> I went out and purchased a ga-ex58-ud5, partly because I'd heard reports
> of it working in Linux with a few different configurations, and also
> because I know GB released a beta BIOS in response to community requests
> for proper VT-d support.
>
> The spec page for the 930 does not specifically list VT-d, and I could use
> another CPU anyway, so I bought a Xeon E5670.
>
> I enable VT-d and once again, rcu_shed detected HardLock on cpu0.  Kthread
> starved for 769 jiffies!
>
> It is essentially the exact same error as with the Rampage II Gene.
>
> At this point I start looking for a software problem.  I'm using the
> latest Debian, and the kernel is 4.4.X.  I installed a 4.2 kernel and tried
> again.
>
> The same thing happened, except that now rcu_shed detects "stalls", not
> HardLock, on cpu0.   The system does not boot beyond that point (this
> happens right as the kernel is loaded at the beginning of boot).
>
> I'm not sure if this distinction is helpful.  The system hangs well before
> logging, and there is no kernel dump.
>
> I took a picture of my screen with the older kernel (stalls not
> hardlocks), and attached it.
>

Still not attached.


> I'm using Proxmox 4.2 VE (latest), which I think I recall reading uses an
> Ubuntu kernel.
>
> I attempted a couple of LiveCDs, only to find they don't use grub, and the
> Intel_iommu parameter does nothing in isolinux.
>

Hmm, usually just a matter of hitting <tab> and adding the option, it's
definitely possible to do this.


> I'm not sure how to proceed from here, aside from buying new hardware.
> X58 is my only option for LGA1366, and comparable LGA2011 stuff is not
> cheap.
>
As discussed in another recent thread, LGA2011 SandBridge-EP processors are
cheap, but motherboard prices are verging on absurd.
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