Re: In place kexec

Neil Horman
2010-07-29T13:43:50Z

On Wed, Jul 28, 2010 at 03:02:19PM -0700, Eric W. Biederman wrote:
> "H. Peter Anvin" <hpa@zytor.com> writes:
>
> > We are getting a claim that the qla driver corrupts memory after a
> > kexec, apparently due to a DMA engine left running in the before-kernel.
> >
> > For an in-place kexec (as opposed to a crash dump kexec, where we switch
> > into dedicated memory), what shutdown paths get executed?
>
> It is the normal reboot path, so the device shutdown method gets
> executed.
>
> Eric
>
Check your iommu. We've had lots of problems with them in the past, and in the
crash path we explicity leave the iommu on now, whereas the normal shutdown path
turns it off. If some other dma-capable device doesn't shut down properly and
keeps dma operations going, you're liable to get memory corruption when the
iommu re-initalizes.

Neil

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