Re: [Xen-devel] Debugging Xen early boot

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.05.16 at 14:31, <Kelly.Zytaruk@xxxxxxx> wrote:
> As for the other question I am still curious as to how to debug early Xen.  
> How was __start_xen written and tested, what sort of tools were used to debug 
> it and get it working right?

I don't know how it was done here, but having been through the
exercise of debugging early boot code in other environments, I
can only say: Get creative. E.g. leverage whatever storage you
have that persists across at least a warm reboot. Depending on
system I have found e.g. video RAM or some of the I/O ports in
the 0x80-0x8f range usable. I also recall that on one specific
box I had to resort to using some of the CMOS non-volatile RAM
or even the RTC registers that don't change rapidly.

>  What do I do in situations where I absolutely 
> can't get serial working properly?

Get serial working properly ;-) ? Or try USB (EHCI). Or use text mode
video output.

Jan


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