> On Tue, Apr 06, 2010 at 07:51:06PM +0200, Joerg Roedel wrote:
> > On Tue, Apr 06, 2010 at 10:42:57AM -0700, Chris Wright wrote:
> > > * Joerg Roedel (
joro@8bytes.org) wrote:
> > > > On Sun, Apr 04, 2010 at 02:44:36AM -0700, Eric W. Biederman wrote:
> > > > > Joerg Roedel <joro@8bytes.org> writes:
> > > > >
> > > > > > On Sun, Apr 04, 2010 at 09:24:30AM +0200, Bernhard Walle wrote:
> > > > > >> Am 03.04.10 19:49, schrieb Eric W. Biederman:
> > > > > >> > Not a problem. We require a lot of things of the kdump kernel,
> > > > > >> > and it is immediately apparent in a basic sanity test.
> > > > > >>
> > > > > >> Also, in most cases (for example: distribution kernels), the kdump
> > > > > >> kernel nowadays is identical to the running kernel. So, if the running
> > > > > >> kernel has IOMMU support, the kdump kernel also has.
> > > > > >
> > > > > > Yes, I know. But is that a requirement for kexec?
> > > > >
> > > > > For normal kexec no. That path is expected to do a clean hardware
> > > > > shutdown.
> > > > >
> > > > > For kexec on panic aka kdump the requirement is that your your crash
> > > > > kernel be able to initialize your hardware from any state it can be
> > > > > put in.
> > > >
> > > > Ok, if you show me where this is documented for everybody then I am
> > > > probably convinced :-)
> > > > We should fixup the gart initialization anyway.
> > >
> > > So, you planning to pull in all 4 patches then?
> >
> > Yes, I will apply them tomorrow and write a fix for the GART issue this
> > may introduce.
> >
>
> Hi Joerg,
>
> Going through the old mail thread, I think the commit you pointed to was
> primarily introduced to solve kexec + GART issue and not necessarily kdump
> issue.
>
> In fact disabling IOMMU patch was introduced by you.
>
> Author: Joerg Roedel <joerg.roedel@amd.com>
> Date: Tue Jun 9 17:56:09 2009 +0200
>
> x86: disable IOMMUs on kernel crash
>
> If the IOMMUs are still enabled when the kexec kernel boots access to
> the disk is not possible. This is bad for tools like kdump or anything
> else which wants to use PCI devices.
>
> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
>
> I am assuming you introduced this patch because you faced issues with
> amd-iommu and not GART.
>
> So basically GART should have been working with kdump even before you
> introduced disabling iommu patch in kdump path.
