Re: [Xen-devel] [PATCH 03/27] Guest setup: allow the amount of RAM to be a runvar

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Dec 11, 2014 at 01:57:59PM +0100, Dario Faggioli wrote:
> On Thu, 2014-12-11 at 12:05 +0000, Wei Liu wrote:
> > On Wed, Dec 10, 2014 at 07:09:18PM +0100, Dario Faggioli wrote:
> > > diff --git a/Osstest/TestSupport.pm b/Osstest/TestSupport.pm
> > > index a3b6936..cdff8d5 100644
> > > --- a/Osstest/TestSupport.pm
> > > +++ b/Osstest/TestSupport.pm
> > > @@ -1460,11 +1460,12 @@ sub prepareguest_part_xencfg ($$$$$) {
> > >      my ($ho, $gho, $ram_mb, $xopts, $cfgrest) = @_;
> > >      my $onreboot= $xopts->{OnReboot} || 'restart';
> > >      my $vcpus= guest_var($gho, 'vcpus', $xopts->{DefVcpus} || 2);
> > > +    my $memory= guest_var($gho, 'memory', $xopts->{DefMem} || $ram_mb);
> > >      my $xoptcfg= $xopts->{ExtraConfig};
> > >      $xoptcfg='' unless defined $xoptcfg;
> > >      my $xencfg= <<END;
> > >  name        = '$gho->{Name}'
> > > -memory = ${ram_mb}
> > > +memory = ${memory}
> > 
> > You made ram_mb redundant.
> >
> Did I? My idea was to use it as default, if the runvar is not defined...
> That is what I though this line does (and I'm quite sure I tested it
> actually does that):
> 
> my $memory= guest_var($gho, 'memory', $xopts->{DefMem} || $ram_mb);
> 
> But, perhaps, I'm not getting what you mean by "redundant"...

Sorry, I missed the "|| $ram_mb".

In any case, having two way of specifying guest memory and one might
shadow the other is a bit subtle to me. One might be affected by a
guest runvar stored in other places and confusingly find out $ram_mb
doesn't work in his / her own script...

> 
> >  And this seems to be deep in the call chain
> > which has subtle knock on effect.
> > 
> Sorry, I don't get what you mean here.
> 

prepareguest_part_xencfg is not exported to guest and user might not
have a good idea why $ram_mb he / she specifies doesn't work.

Wei.


> Thanks and Regards,
> Dario
> 
> -- 
> <<This happens because I choose it to happen!>> (Raistlin Majere)
> -----------------------------------------------------------------
> Dario Faggioli, Ph.D, http://about.me/dario.faggioli
> Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)
> 



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