Re: 32-bit ARM guest on 64-bit ARM Xen

[Julien Grall <julien.grall@citrix.com>]

On 28/04/2015 20:14, Robert VanVossen wrote:
> Hello,

Hi Robert,

> I was wondering, what is the current state of running a 32-bit ARM guest running
> on a 64-bit Xen for ARM. I was working on getting the minios from
> https://github.com/talex5/xen/commits/next built and running as a guest on an
> emulated Cortex-A53. I have gotten Xen and 64-bit Linux guests running in the
> emulated environment, but I ran into some issues with the 32-bit guests.

I used 32-bit kernel on 64-bit hardware recently without no issue. 
AFAICT, 32-bit guest as always worked on Xen. Which version on Xen are 
you running?

Also, silly question, does your hardware supports 32-bit instructions? 
I.e were you able to run Linux 32-bit on baremetal?

> When I tried to run them, I got the following:
>
> Parsing config from /etc/xen/mini.cfg
> (XEN) Hypervisor Trap. HSR=0x2000000 EC=0x0 IL=1 Syndrome=0x0

This looks like an issue with Xen running on your hardware. EC = 0x0 
means "Exception with an Unkwnown reasons".

> (XEN) CPU0: Unexpected Trap: Hypervisor
> (XEN) ----[ Xen-4.6-unstable  arm64  debug=y  Not tainted ]----
> (XEN) CPU:    0
> (XEN) PC:     00000000002413c8 schedule_tail+0x248/0x2dc

schedule_tail contains the code to context switch from one domain to 
another one.

Can you run addr2line on the xen-syms with the address in PC and give 
the result?

Regards,

-- 
Julien Grall