Re: xen-unstable on HP dc7800 simply reboots

[John Byrne <john.l.byrne@hp.com>]

John Byrne wrote:
> Keir Fraser wrote:
>> On 23/10/07 17:49, "John Byrne" <john.l.byrne@hp.com> wrote:
>>
>>> Does anyone know what is wrong or can tell me how to go about debugging
>>> this? The dmesg output from booting the Ubuntu 2.6.22-14-server kernel
>>> is attach in the hope that it will provide some useful information.
>>
>> I suggest binary-chopping to find the offending changeset. Some early
>> boot-time stuff went in over the past few days, so for example try 
>> reverting
>> to 16130 and see if that has the same problem. Go back another 30, or
>> forward 15, changesets depending on whether that works or not. I suspect
>> this issue is quite new, so it shouldn't take too long to narrow down.
> 
> Actually, it a few months old. xen-unstable 15236 is the last changeset 
> that Xen doesn't immediately reboot.
> 

Littering the early boot code with putc() and comparing the code's 
behavior on a machine that actually boots, I've found that the call to 
get_memory_map from trampoline.S is the root of all evil. If that is 
called, then the trampoline fails to make it back to protected mode from 
real mode. I am still working to identify the specific problem.

John