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

[Brian Yglesias]

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 configuratioThe 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. 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. 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. Any help is much appreciated.
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