[patch] ia64: make PA() work for both physical identity-mapped virtual addresses

[Simon Horman]

On Mon, Oct 06, 2008 at 04:00:49PM -0600, Bjorn Helgaas wrote:
> On Monday 06 October 2008 3:32:10 pm Simon Horman wrote:
> > On Mon, Oct 06, 2008 at 09:24:03AM -0600, Bjorn Helgaas wrote:
> > > The EFI Runtime Services Table contains pointers to ia64 function
> > > descriptors.  On existing, pre-Tiano, firmware, SetVirtualAddressMap()
> > > converts *all* these pointers from physical to virtual.  On Tiano-based
> > > firmware, the pointer to the SetVirtualAddressMap() function descriptor
> > > is not converted, so it remains a physical pointer.
> > >
> > > The ia64 kexec purgatory patches the SetVirtualAddressMap() function
> > > descriptor so that when the new kernel calls SetVirtualAddressMap(), it
> > > never reaches firmware.  Instead, it calls a dummy function that just
> > > returns success.
> > >
> > > Purgatory runs in physical mode, so it must convert the pointer from the
> > > RuntimeServicesTable to a physical address.  This patch makes that
> > > conversion work both for old firmware (where the pointer is an identity-
> > > mapped virtual address) and new Tiano firmware (where the pointer is a
> > > physical address).
> > >
> > > Without this patch, kexec on Tiano firmware causes an MCA because
> > > ia64_env_setup() subtracts PAGE_OFFSET from a physical address and ends
> > > up with an invalid physical address.  Referencing that address causes
> > > the MCA.
> > >
> > > Signed-off-by: Bjorn Helgaas <bjorn.helgaas at hp.com>
> >
> > Thanks Bjorn, applied.
> 
> Thanks!
> 
> Any idea when you'll make another kexec-tools release?  I have a
> Red Hat feature request in for RHEL6, and they'll need to know
> what kexec-tools version to look for.  RH will get the latest
> for RHEL6, but I really don't know when they'll start putting
> that together.
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=463477

I'm happy to make one soon if that helps.

-- 
Simon Horman
  VA Linux Systems Japan K.K., Sydney, Australia Satellite Office
  H: www.vergenet.net/~horms/             W: www.valinux.co.jp/en