Subject: Re: [PATCH 1/8] pseries: phyp dump: Docmentation

From: Michael Ellerman <[email-masked]>
Date: Thu, 10 Jan 2008 15:52:31 +1100

On Wed, 2008-01-09 at 22:12 -0600, Linas Vepstas wrote:
> On 09/01/2008, Olof Johansson <[email-masked]> wrote:
> > On Wed, Jan 09, 2008 at 08:33:53PM -0600, Linas Vepstas wrote:
> >
> > > Heh. That's the elbow-grease of this thing.  The easy part is to get
> > > the core function working. The hard part is to test these various configs,
> > > and when they don't work, figure out what went wrong. That will take
> > > perseverence and brains.
> >
> > This just sounds like a whole lot of extra work to get a feature that
> > already exists.
> 
> Well, no. kexec is horribly ill-behaved with respect to PCI. The
> kexec kernel starts running with PCI devices in some random
> state; maybe they're DMA'ing or who knows what. kexec tries
> real hard to whack a few needed pci devices into submission
> but it has been hit-n-miss, and the source of 90% of the kexec
> headaches and debugging effort. Its not pretty.

Isn't that what EEH and the IOMMU are for? :)

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person