RE: Intel IOMMU on Dell Latitude E6400, Lenovo X200 & DellPrecision T5400

[Yu, Fenghua]

>We had reported more details @
>https://bugzilla.redhat.com/show_bug.cgi?id=479996 and
>http://bugzilla.kernel.org/show_bug.cgi?id=11821

Look into http://bugzilla.kernel.org/show_bug.cgi?id=11821
and find that:

wlan0: Failed to config new SSID to the low-level driver
BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
IP: [<ffffffff8037cf1f>] pci_find_upstream_pcie_bridge+0x1f/0xa0
...
[<ffffffff80386808>] get_domain_for_dev+0x58/0x620
 [<ffffffff8029574d>] ? __alloc_pages_internal+0xed/0x4f0
 [<ffffffff803870f8>] get_valid_domain_for_dev+0x18/0x150
 [<ffffffff803875e7>] intel_map_single+0x47/0x160
 [<ffffffff802b8726>] ? alloc_pages_current+0x76/0xf0
 [<ffffffff8038777f>] intel_alloc_coherent+0x7f/0xb0
...

Wireless LAN could cause the NULL pointer access in get_domain_for_dev() which is IOMMU function.

As an experiment, could you disable wireless lan on your machine and try to boot IOMMU kernel?

Thanks.

-Fenghua
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