Re: [PATCH v2] xen/console: buffer and show origin of guest PV writes

[Keir Fraser <keir.xen@gmail.com>]

On 09/09/2013 06:46, "Daniel De Graaf" <dgdegra@tycho.nsa.gov> wrote:

> On 09/09/2013 07:13 AM, Keir Fraser wrote:
>> On 16/08/2013 20:01, "Daniel De Graaf" <dgdegra@tycho.nsa.gov> 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.
>>> 
>>> Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
>> 
>> This seems good, but, if we process and buffer dom0's output, we lose the
>> possibility of running a terminal session in dom0 over the Xen console.
>> Personally I do that quite a bit -- serial access only, get Xen's debugging
>> there, but also can log in to dom0. Does noone else??
> 
> I do care about this use case (I also use it rather often), and it is
> preserved
> - this patch explicitly does not buffer or insert characters in dom0's output.
> This means that we waste the 80-byte buffer for dom0, but I didn't think it
> was
> worth special-casing dom0 there too (also, doing that might break a PVH dom0
> that uses the HVM output - if that method is available, which I did not
> check).

That's great, but then the patch header is wrong as the output buffering is
not used by *all* domains. Make it clear that dom0 is unaffected and then:
Acked-by: Keir Fraser <keir@xen.org>

 -- Keir