kexec reboot broken with ioatdma?

Simon Horman horms at
Wed Dec 16 18:36:13 EST 2009

On Wed, Dec 16, 2009 at 03:04:03PM -0800, Roland Dreier wrote:
>  > from a kexec point of view I believe that the preferred option is the
>  > former - shutdown the device so it can be initialised using standard paths
>  > in the second kernel.
> OK... however I'm not suggesting a separate kexec initialization path,
> simply adding a reset of the device in the standard initialization.
> This would be fairly normal for other types of device; for example, the
> BIOS may have left a NIC in an undefined state due to network boot.  Of
> course BIOS is unlikely to use an IOAT DMA engine but the principle of
> limiting assumptions about platform state still stands I think.

If its reset in a standard path, then yes that seems sensible to me.
I'm mainly concerned about avoiding something along the lines of:

	if (is_booting_from_kexec)

> >From a quick look, it seems tricky to get a clean shutdown of IOAT stuff
> since there doesn't seem to be a clean ordering that makes sure the
> ioatdma stuff is shutdown after everything using it.
>  - R.
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