On Tue, 2015-07-14 at 18:41 +0300, Oleksandr Dmytryshyn wrote: > On Tue, Jul 14, 2015 at 6:31 PM, Oleksandr Dmytryshyn > <oleksandr.dmytrys...@globallogic.com> wrote: > > > > Hi, Ian. Thank You for the responce. > > > > Currently have 3 kernels: Thin Dom0 (privileged), DomD (privileged > > driver domain), > > DomU (not privileged) > > > > On Mon, Jul 13, 2015 at 12:04 PM, Ian Campbell <ian.campb...@citrix.com> > > wrote: > > > The way we deal with this elsewhere in the kernel is that we only ever > > > do grant mappings over ballooned out pages, which are allocated via > > > gnttab_alloc_pages. That way when they are unmapped the page is expected > > > to be entry and no backing mfn is lost. The page can then subsequently > > > be ballooned back in as normal. > > We can not use this case because our DRM driver has already allocated memory > > which will be mapped later. > > > > > There is an additional quirk for a 1:1 mapped dom0 which is that we > > > don't actually decrease reservation when ballooning, but keep the 1:1 > > > mfn in anticipation of ballooning it back in later. > > Could You please tell me a bit more information about this quirk. How this > > quirk > > can be enabled? > > > > > If you can't arrange to use already ballooned buffers for your DMA > > > buffer then you will need to manually balloon it out before and balloon > > > it back in later. > > This is my case. I'll try to to this. > Here is one question. > Could anybody tell me how to manually balloon a page in/out?
Look at how the balloon driver does it, the hypercalls you want are XENMEM_(increase|decrease)_reservation. Ian. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
