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Re: [Xen-devel] Xen 4 serial hangs during boot

>>> On 23.07.12 at 22:53, "Christopher S. Aker" <caker@xxxxxxxxxxxx> wrote:
> On 7/20/12 3:59 PM, Keir Fraser wrote:
>> Then it is Xen doing something to kill the serial interrupt. ;-) I haven't
>> seen anything like this reported before. Not sure what to suggest really...
>> Gather debug output from interrupt-related debug keys (via the xl debug-keys
>> interface) I suppose. I think that would be 'i' and 'z' keys. That plus Xen
>> and dom0 boot logs... something might become apparent.
> We hit this again today, and I grabbed boot and debug-keys output:
> http://theshore.net/~caker/xen/BUGS/serial/log.txt 

This isn't even 8k that make it over, whereas the transmit buffer
is 16k, and dropping of characters would only start when it first
got full.

The part of the data that didn't make it out isn't big enough to
overflow the buffer - to check whether that would actually
happen, could you increase the log level of both hypervisor and
Dom0 kernel? To me this all (particularly the fact that you can
make the data appear combined with the amount of data not
being big enough to fill the buffer) looks as if there was some
buffering happening outside of the control of Xen. Did you check
whether this is possibly a problem with the remote end?

Does this also happen with "sync_console"? Did you check
whether disabling the use of the associated IRQ makes any
difference, as suggested by Konrad (I think)?

Does the port work flawlessly on native Linux?


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