[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-users] Debugging DomU

Hi Ian,

On 26/05/2015 11:03, Ian Campbell wrote:
On Tue, 2015-05-26 at 10:48 +0200, Julien Grall wrote:
I can actually step reliably through the startup code with the JTAG
now. It looks like that instruction was from the
"putstr("Decompressing kernel...");" in
With that change, xenctx shows me a much more reasonable value for
PC and SVC_LR. Digging around then led me to disable CONFIG_DEBUG_LL,
because it seems that the problems I'm seeing relate to trying to
print something. With that, I think it's getting further still. Xenctx
now tells me that it ends up in __loop_delay(), with LR pointing to
panic(). I'm having problems reproducing this with the JTAG, though
(it seems to behave slightly differently when I'm using JTAG to debug
it), and I'm not seeing any output from DomU.

I confirm the CONFIG_DEBUG_LL should be disabled in Xen guest because
it's not portable and not supported.

So long as it is configured to use the same underlying device as Xen's
console then it shouldn't result in crashes, I thought, due to the very
simplistic uart stuff in xen/arch/arm/vuart.c.

For dom0 yes. But we are talking about domU here.

The UART emulated by vuart.c re-uses the hardware UART region. In domU, this region may clash with other part of the memory layout. Therefore it's not possible to use it.


Julien Grall

Xen-users mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.