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

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
> >
> > ---
> >
> > 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

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