[PATCH] PCI: Clear Bus Master bit only on kexec reboot

Greg KH gregkh at linuxfoundation.org
Wed Nov 27 16:22:27 EST 2013

On Wed, Nov 27, 2013 at 12:59:40PM -0700, Khalid Aziz wrote:
> On 11/27/2013 12:38 PM, ebiederm at xmission.com wrote:
> >Khalid Aziz <khalid.aziz at oracle.com> writes:
> >
> >>Add a flag to tell the PCI subsystem that kernel is shutting down
> >>in prepapration to kexec a kernel. Add code in PCI subsystem to use
> >>this flag to clear Bus Master bit on PCI devices only in case of
> >>kexec reboot. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=63861
> >>and avoids any other issues caused by clearing Bus Master bit on PCI
> >>devices in normal shutdown path. This patch is based on discussion at
> >>http://marc.info/?l=linux-pci&m=138425645204355&w=2
> >
> >Scratches head.
> >
> >Given that most devices already call pci_disable_device which clears the
> >bus master bit how does this change anything meaningful?
> >
> >Is is the problem here that most drivers are lazy and have a noop
> >shutdown method?
> Yes, that is exactly the problem.

Then fix the drivers please.  It's not as if you don't have access to
the source for them all...

greg k-h

More information about the kexec mailing list