interspersed IOMMU messages in skylake output

[lsf37]

skylake produces output such as

IOMMU: DMA write page fault from 0xa0 (bus: 0x0/dev: 0x14/fun: 0x0) on address 0x0:dc2f9000 with reason code 0x5

interleaved with normal test output, which sometimes confuses the test driver into thinking tests have not succeeded.

If the message is expected, it should be suppressed. If it is not expected, it should be investigated.

An example is here

[kent-mcleod]

According to a lspci under linux:

00:14.0 USB controller: Intel Corporation Sunrise Point-H USB 3.0 xHCI Controller (rev 31)

Some USB device is trying to perform DMA writes once seL4 starts it seems. Does that machine have any USB devices attached to it that the other haswell machines don't?

[kent-mcleod]

All of the usb devices go through that USB controller:

$ lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 006: ID 06cb:0009 Synaptics, Inc. Composite TouchPad and TrackPoint
Bus 001 Device 005: ID 04b3:3018 IBM Corp. UltraNav Keyboard
Bus 001 Device 003: ID 04b3:3016 IBM Corp. UltraNav Keyboard Hub
Bus 001 Device 004: ID 413c:2002 Dell Computer Corp. SK-8125 Keyboard
Bus 001 Device 002: ID 413c:1002 Dell Computer Corp. Keyboard Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

$ ls -alh /sys/bus/usb/devices/
total 0
drwxr-xr-x 2 root root 0 Dec  7 11:35 .
drwxr-xr-x 4 root root 0 Dec  7 11:26 ..
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-0:1.0 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-0:1.0
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-3 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-3
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-3.1 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3.1
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-3:1.0 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3:1.0
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-3.1:1.0 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3.1/1-3.1:1.0
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-3.1:1.1 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3.1/1-3.1:1.1
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-5 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-5
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-5:1.0 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5:1.0
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-5.3 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.3
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-5.3:1.0 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.3/1-5.3:1.0
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-5.3:1.1 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.3/1-5.3:1.1
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-5.4 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.4
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-5.4:1.0 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.4/1-5.4:1.0
lrwxrwxrwx 1 root root 0 Dec  7 11:26 1-5.4:1.1 -> ../../../devices/pci0000:00/0000:00:14.0/usb1/1-5/1-5.4/1-5.4:1.1
lrwxrwxrwx 1 root root 0 Dec  7 11:26 2-0:1.0 -> ../../../devices/pci0000:00/0000:00:14.0/usb2/2-0:1.0
lrwxrwxrwx 1 root root 0 Dec  7 11:26 usb1 -> ../../../devices/pci0000:00/0000:00:14.0/usb1
lrwxrwxrwx 1 root root 0 Dec  7 11:26 usb2 -> ../../../devices/pci0000:00/0000:00:14.0/usb2

[lsf37]

@wom-bat do you know if skylake has any USB devices attached that would be causing this?

[lsf37]

Peter says it might be the keyboard/mouse that is plugged in.