Re: Intel IOMMU on Dell Latitude E6400, Lenovo X200 & Dell Precision T5400

[Oleg Orel <oorel@vmware.com>]

Yu, Fenghua wrote:
>   
>> 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
>   
Yu,
I did it already yesterday. It didn't help. It fact I had disable all 
disableble devices, also, on T5400 when is failing as well, we do not 
have a wireless.