Re: debian stretch dom0 + xen 4.9 fails to boot

["Jan Beulich" <JBeulich@suse.com>]

>>> On 07.06.17 at 17:06, <Paul.Durrant@citrix.com> wrote:
>> From: Jan Beulich [mailto:JBeulich@suse.com]
>> Sent: 07 June 2017 13:56
>> >>> On 07.06.17 at 14:46, <Paul.Durrant@citrix.com> 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. 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.

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...

Jan


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