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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.06.17 at 14:46, <Paul.Durrant@xxxxxxxxxx> wrote:
>>  -----Original Message-----
>> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: 07 June 2017 13:00
>> 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 13:55, <Paul.Durrant@xxxxxxxxxx> wrote:
>> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> >> Sent: 07 June 2017 12:50
>> >> 2) Provide the E820 map of that box.
>> >> I'm suspecting the BIOS might use an EBDA without recording it in
>> >> the low BIOS data area. If it's reported in E820 that would then
>> >> likely be the final kick for us to obey to the E820 map when
>> >> determining where to put the trampoline.
>> >>
>> >
>> > The stretch kernel booted bare-metal reports:
>> >
>> > [    0.000000] e820: BIOS-provided physical RAM map:
>> > [    0.000000] BIOS-e820: [mem 0x0000000000000000-0x00000000000963ff]
>> usable
>> > [    0.000000] BIOS-e820: [mem 0x0000000000096400-0x000000000009ffff]
>> reserved
>> 
>> There we go. Subtracting 4k may then even be too little (depending
>> what EBDA and low memory values the system reports). Of course
>> it would be a BIOS bug if they reported some memory they use for
>> themselves through only E820, as that interface is not required to
>> be present, and really, really old software wouldn't even know
>> about it and would hence also be in trouble.
>> 
> 
> Neither 4k nor 8k seemed to be enough. Even subtracting another
> 64k doesn't work.

That's rather unexpected.

> 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!

Jan


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