On 23/06/16 16:10, Jan Beulich wrote: >>>> On 23.06.16 at 16:55, <andrew.coop...@citrix.com> wrote: >> On 20/06/16 13:52, Jan Beulich wrote: >>> +/* >>> + * Note that this value is effectively part of the ABI, even if we don't >> need >>> + * to make it a formal part of it. Hence this value may only be changed if >>> + * accompanied by a suitable interface version increase. >>> + */ >>> +#define HVMCTL_iter_shift 8 >>> +#define HVMCTL_iter_mask ((1U << HVMCTL_iter_shift) - 1) >>> +#define HVMCTL_iter_max (1U << (16 + HVMCTL_iter_shift)) >> This (mis)use of the cmd parameter is surely no longer necessary, given >> that there is space in xen_hvmctl_t to encode continuation information? > There's no misuse of cmd anymore. This is just use to make the 16-bit > continuation value (the opaque structure member) cover a more useful > range, and at once avoid doing the preemption check on every > iteration.
Ah ok, but it does leave the minimum iteration at 256, which could easily be too large, depending on the underlying operation. In this case, I think it would be far better to bump the cmd field to 32 bits, and opaque to 64bits, which affords us far more flexibility. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
