Re: [Xen-devel] Volunteers required for 4.2 TODO items (Re: 4.2 TODO update)

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2012-03-12 at 16:00 +0000, Lin Ming wrote:
> On Mon, Mar 12, 2012 at 8:22 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Mon, 2012-03-12 at 12:11 +0000, Ian Campbell wrote:
> >> There are several things below which are in need of a volunteer to take 
> >> care of them...
> 
> Hi,
> 
> I'm a newcomer.
> Could you share more details about the requirements?
> 
> >
> > Specifically:
> >
> >> tools, blockers:
> >> [...]
> >>       * xl support for "rtc_timeoffset" and "localtime" (Nobody AFAICT)
> 
> Are these parameters to be added for some xl subcommand?
> What are they used for?

These should be options which can be specified in the domain
configuration file for HVM guests. They control the offset of the
guest-visible emulated RTC from the host time -- IOW they control the
time which the guest sees.

These options are supported by xm/xend and need to be implemented for xl
in a compatible way. This means exposing suitable fields in the libxl
API (probably as fields in libxl_domain_build_info) and arranging for xl
to parse the configuration file options.

Some amount of reverse engineering of xend will be required to figure
out what the actual meaning of those options in order to implement in a
compatible way but AFAIK rtc_timeoffset is the offset between host time
and guest time. localtime I think means to specify whether the emulted
RTC appears as UTC or is offset by the host.

Having figured out the meaning libxl needs to arrange to call
xc_domain_set_time_offset with the right values.

I think much of the related xend code is in
tools/python/xen/xend/image.py but you might need to grep about a bit.

> >>       * Domain 0 block attach & general hotplug when using qdisk backend
> >>         (need to start qemu as necessary etc)
> >> tools, nice to have:
> >> [...]
> >>       * xl support for autospawning vncviewer (vncviewer=1 or otherwise)
> 
> Could you tell more detail?

xm/xend supports a configuration file option "vncviewer=1" which causes
xend to automatically spawn vncviewer with the correct options (e.g.
port number) when doing "xm create". We would like the same for "xl
create".

As well as a config file option I think a command line option to "xl
create" would also be useful, similar to '-c' which automatically
connects to the virtual serial console. e.g '-V' perhaps.

I guess we would want a libxl interface similar to
libxl_primary_console_exec and xl support to call it when appropriate.
overall it should look a lot like the console spawning stuff.

> >>         (Nobody AFAICT)
> >>       * support for vif "rate" parameter (No one, AFAICT)
> 
> It's a kernel module parameter(xen-4.1.2/tools/vnet/vnet-module), right?

I don't think so, this is network rate limiting as implemented by
netback. Mathieu Gagnà is already taking care of this so I won't go into
any further detail (which is lucky, because I'm fuzzy about the details
myself).

> 
> >
> > #1,#3 & #4 are reasonably simple libxl/xl features possibly suitable for
> > a newcomer who is interested in getting started with toolstack level
> > stuff.
> >
> > #2 is a bit more involved.
> >
> > Any takers?
> 
> I'm a new comer and I'd like to get start from here.

Please do let us know if you decide to take on one of the tasks.

Ian.



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