Re: [PATCH RFC] xen/console: buffer and show origin of guest PV writes

[Daniel De Graaf <dgdegra@tycho.nsa.gov>]

On 08/13/2013 12:40 PM, Pasi Kärkkäinen wrote:
> On Tue, Aug 13, 2013 at 12:34:19PM -0400, Daniel De Graaf wrote:
>> Guests other than domain 0 using the console output have previously been
>> controlled by the VERBOSE define, but with no designation of which
>> guest's output was on the console. This patch converts the HVM output
>> buffering to be used by all domains, line buffering their output and
>> prefixing it with the domain ID. This is especially useful for debugging
>> stub domains during early boot.
>>
>> Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
>>
>> ---
>>
>> A few questions for discussion (the reason this is an RFC):
>>
>> 1. HVM guests' output is currently limited to printable characters; do
>> we want to implement the same restriction on PV guests?
>>
>> 2. The prefix on the serial console for PV output is "(XEN) d5: ", while
>> HVM output is still "(XEN) HVM5: "; should these be made consistent?
>>
>> 3. Should we change to allowing console output by default, since it is
>> now controlled by log levels?
>>
>
> Also having timestamps before the log entries would be nice (like Linux has)..
>
> -- Pasi

Since this uses printk, if timestamps are turned on with opt_console_timestamps,
they will beadded to the output. It looks like the timestamp only has 1 second
resolution, unlike Linux - it might be useful to update that.

-- 
Daniel De Graaf
National Security Agency