Kernel panics when using kexec for rebooting

[Dave Lloyd]

On Tue, May 14, 2013 at 6:14 PM, Eric W. Biederman
<ebiederm at xmission.com> wrote:

>
> Oh. Yeah.  IB definitely sets up memory for ongoing dma.  So if it
> doesn't have a shutdown method and IB traffic comes in during boot just
> about anything cood happen.
>
>> I'm inclined to chalk the ACPI Error mesages up to potentially buggy
>> BIOS/hardware from the vendor since pata_amd and pata_acpi are in wide
>> use and I would expect to see more issues reported were there truly an
>> issue with rebooting with kexec and not unloading pata_amd and
>> pata_acpi.
>
> Maybe.  Or it might be luck of timing, which memory was stomped when
> incomming IB packets stomped on memory.
>
> Eric
>

Removing the infiniband drivers in /etc/init.d/halt right before the
kexec -e definitely seems to have done the trick. Thanks!

My follow up question is, if we are clearing the bus master DMA bit,
why are the Mellanox not reset or at least stop doing DMA until the
driver is loaded again? Is this a case of the Mellanox hardware
needing an extra poke to do the right thing?

--dlloyd