>>> On 15.01.16 at 11:09, <ian.campb...@citrix.com> wrote: > On Thu, 2016-01-14 at 03:04 -0700, Jan Beulich wrote: >> - ARM side unimplemented (and hence libxc for now made cope with both >> models), > > So, one model is the one described in the commit message: > >> - zero (success, everything done) >> - positive (success, this many done, more to do: re-invoke) >> - negative (error) > > What is the other one? I'd expect ARM to already implement a subset of this > (i.e. 0 or negative, perhaps with a subset of the possible errno values), > which I'd then expect libxc to just cope with without it constituting a > second model.
Well, first of all ARM doesn't get switched away from the current model (yet), i.e. returning -E2BIG out of do_domctl(). And then the difference between what the patch implements and what the non-commit message comment describes is how errors get handled: The patch makes a negative error value returned upon error, with the caller having no way to tell at what point the error occurred (and with a best effort undo in the case of "map"). The described alternative would return the number of succeeded entries unless an error occurred on the very first MFN, without any attempt to undo the part that was done successfully. I.e. it would leave it to the caller to decide what to do, and whether/when to roll back. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
