Re: [PATCH] tools/xl: Add stubdomain_cmdline option to xl.cfg

[Jason Andryuk <jandryuk@xxxxxxxxx>]

On Wed, Jul 21, 2021 at 8:50 AM Ian Jackson <iwj@xxxxxxxxxxxxxx> wrote:
>
> Jason Andryuk writes ("Re: [PATCH] tools/xl: Add stubdomain_cmdline option to 
> xl.cfg"):
> > I think this option actually sets the string, so you want "Set
> > B<STRING> as the device-model stubdomain kernel command line." or
> > something equivalent?
> >
> > With a suitable change,
> > Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>
>
> Does it then override an existing commandline calculated by libxl ?

Today, libxl doesn't handle a command line string for the stubdom
kernel, so it defaults to an empty string.

> Often people want to just add an option, so a config setting to append
> things is useful (but one to override it completely is useful too).

Yes, they can both be useful.  Append is sufficient until you want to
override or remove an option that is already included.  Set can be
tedious since you have to copy the existing options before appending
your new one.

Anyway, I just wanted the documentation to match the implementation.
Looks like xl.cfg.5.pod.in says Append for cmdline/root/extra, so
Scott was repeating that.  Looking around, aside from concatenating
root and extra in xl_parse.c:parse_cmdline(), libxl doesn't seem to
calculate command lines.  If libxl is reserving the right to calculate
cmdline in the future, then keeping Append is fine by me.

Regards,
Jason