> -----Original Message----- > From: Andrew Cooper <andrew.coop...@citrix.com> > Sent: 13 November 2019 14:05 > To: Durrant, Paul <pdurr...@amazon.com>; xen-devel@lists.xenproject.org > Subject: Re: [Xen-devel] [PATCH] domain_create: honour global > grant/maptrack frame limits... > > On 13/11/2019 13:47, Paul Durrant wrote: > > ...when their values are larger than the per-domain configured limits. > > > > Signed-off-by: Paul Durrant <pdurr...@amazon.com> > > --- > > After mining through commits it is still unclear to me exactly when Xen > > stopped honouring the global values, but I really think this commit > should > > be back-ported to stable trees as it was a behavioural change that can > > cause domUs to fail in non-obvious ways. > > -1. Overriding toolstack settings like this is the same kind of "bad" > as silently converting HAP => Shadow. > > In particular, this breaks one of points of the original per-domain work > to deliberately allow stub xenstored to be configured with tiny > grant/maptrack tables.
Ok, but IMO subtly breaking domUs in the process is not really acceptable behaviour. > > You also break the setting of these parameters in xl.conf. No I don't. xl.conf can still increase values over the command line. > > I'm not defending how the interface changed subtly/unexpected; that was > bad and we should have done better, but this change is just as bad in > the opposite direction. > > The way to fix this is to plumb the Xen default parameters though so > that, in the absence of any explicit configuration (vm.cfg or xl.conf), > libxl can then use "xen cmdline" as a source of configuration, before > falling back to hardcoded numbers. > I agree that is the best way to fix it, but not so easy to backport. So my proposal (via email a few days ago) was that regressions are fixed immediately in this way and then a *proper* fix is done moving forward, which I shall base upon Juergen's patches which should allow easy retrieval of the command line values. Paul _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
