Re: [Xen-devel] Unable to create guest PV domain on OMAP5432

[Volodymyr Babchuk <vlad.babchuk@xxxxxxxxx>]

Hi Jayadev,

On 17 November 2017 at 13:53, Andrii Anisov <andrii_anisov@xxxxxxxx> wrote:
>>
>> Is there a way to debug which one of the above two possibilities has lead
>> to the issue ?
>
> Four years ago I did it in a following way:
>     - wire up to UART2 pins on an expansion connector (this sheet might be
> useful for you: http://www.ti.com/lit/ug/swcu130/swcu130.pdf)
>     - assign UART2 IOMEM ranges to DomU
>     - enable in domu kernel earlyprintk and patch it to output to omap UART2
>
> Nowadays assigning UART2 IOMEM ranges might be a bit more complex due to XEN
> evolution.
>
> Another way is to use JTAG which understands virtualization, and allows you
> to debug DomU.
I want to add some debugging techniques:
 - By tapping CTRL+A three times to switch to XEN console. Then `d`
will show you CPU register states. You will be able to see where your
DomU executes right now. This can help along with addr2line, objdump
and other tools.

 - You can modify traps.c in XEN to crash domain when SMC instruction
is trapped. Then you can put SMC invocation into various parts of
kernel code, to see if it reaches that place. This can help on early
stages, when console is not available.

-- 
WBR Volodymyr Babchuk aka lorc [+380976646013]
mailto: vlad.babchuk@xxxxxxxxx

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