Re: [Xen-devel] debian stretch dom0 + xen 4.9 fails to boot

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 07 June 2017 16:33
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: Julien Grall (julien.grall@xxxxxxx) <julien.grall@xxxxxxx>; Andrew
> Cooper <Andrew.Cooper3@xxxxxxxxxx>; xen-devel(xen-
> devel@xxxxxxxxxxxxxxxxxxxx) <xen-devel@xxxxxxxxxxxxxxxxxxxx>;
> 'BorisOstrovsky' <boris.ostrovsky@xxxxxxxxxx>; Juergen Gross
> <jgross@xxxxxxxx>
> Subject: RE: [Xen-devel] debian stretch dom0 + xen 4.9 fails to boot
> 
> >>> On 07.06.17 at 17:06, <Paul.Durrant@xxxxxxxxxx> wrote:
> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> Sent: 07 June 2017 13:56
> >> >>> On 07.06.17 at 14:46, <Paul.Durrant@xxxxxxxxxx> wrote:
> >> > I guess I'm going to have to try to write some code to log values to
> >> > the VGA buffer to see what is going on.
> >>
> >> Good luck!
> >>
> >
> > That really was too hard... Instead I reverted the patch and stashed EBDA
> > and the initial location of the trampoline and dumped them in
> __start_xen().
> > The EBDA tallies with the E820:
> >
> > (XEN) boot_ebda = 9640
> > .
> > .
> > (XEN) Xen-e820 RAM map:
> > (XEN)  0000000000000000 - 0000000000096400 (usable)
> > (XEN)  0000000000096400 - 00000000000a0000 (reserved)
> >
> > And the initial location of the trampoline appears to be ok...
> >
> > (XEN) orig_trampoline_phys = 86000
> >
> > So, still no clue as to why moving the wakeup code around is messing things
> > up.
> 
> This looks to be turning into a nightmare.

Definitely!

> Since you said it doesn't
> make it to the point where Xen would do any normal output, have
> you been able to narrow down how far it gets? I think this is one
> of the few remaining avenues to gain some more understanding.
> 

Yes, that's what I'm now attempting. Andrew has some serial logging patches 
that I'm going to try to convert to VGA logging.

> One other thing to try might be, with that patch reverted, to fill
> all memory upwards from wakeup_start (or really its low
> memory copy) with a pattern, and later inspect whether anything
> changed (you could of course also simply compare low memory
> copy and original). Or maybe you have tried this already...
> 

No, not done that... sounds like a good idea.

Thanks,

  Paul

> Jan


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