[Xen-devel] Problem porting Xen on ARM

[Frediano Ziglio <freddy77@xxxxxxxxx>]

Hi,
  I'm trying to support this platform
https://wiki.linaro.org/Boards/D01 on Xen. The platform has a slightly
different GIC v2 to support 16 cores (basically ITARGET on GICD was
extended to accomodate 16 bits instead of 8). Did the change and added
support for platform (setting up additional CPUs). Timers are working
fine (I get interrupts).

Now dom0 starts but it stops after a while. I have serial access so I
was able to dump registers and I got this:
http://pastebin.com/rK5Amze8. As you can note last 8 CPUs are idle
while the other 8 are assigned to dom0 (Xen has 16 CPUs while dom0 has
only 8). I noted that CPU 0 is the only one that has no host state. Is
that normal? Should not have state, at least when timer interrupts are
executed. I suspect for some reason does not setup properly the first
CPU.

I still don't know that much ARM architecture so surely I'm doing
something wrong. It's not clear to me which devices should seen by
dom0 and which devices should not be seen, actually
- physical generic timer is hidden by Xen and replaced with a virtual
one (provided with a virtual hardware function);
- should I hide additional timers? Actually if I do Linux hangs trying
to calibrate delays (quite odd, why it does not use generic timer to
do the same?);
- physical GIC is half virtualized (GICD is fully virtualized while
for GICC a virtual physical function is used);
- physical memory is virtualized by Xen (which present only part of it);
- physical serial is hidden (as used for the console);
- I had to hide physical control interface (used to setup additional
CPU) as Linux was attempting to physically initialize the CPUs again;
- Xen add a psci device to replace the physical control interface;
- others are passed (with FDT) trasparently to dom0.

Should I post the FDT before and after Xen handle it?

Regards,
  Frediano

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