> -----Original Message----- > From: Petre Ovidiu PIRCALABU [mailto:ppircal...@bitdefender.com] > Sent: 10 January 2019 15:31 > To: Paul Durrant <paul.durr...@citrix.com>; xen-devel@lists.xenproject.org > Cc: Stefano Stabellini <sstabell...@kernel.org>; Wei Liu > <wei.l...@citrix.com>; Razvan Cojocaru <rcojoc...@bitdefender.com>; Konrad > Rzeszutek Wilk <konrad.w...@oracle.com>; George Dunlap > <george.dun...@citrix.com>; Andrew Cooper <andrew.coop...@citrix.com>; Ian > Jackson <ian.jack...@citrix.com>; Tim (Xen.org) <t...@xen.org>; Julien > Grall <julien.gr...@arm.com>; Tamas K Lengyel <ta...@tklengyel.com>; Jan > Beulich <jbeul...@suse.com>; Roger Pau Monne <roger....@citrix.com> > Subject: Re: [Xen-devel] [RFC PATCH 4/6] vm_event: Use slotted channels > for sync requests. > > On Thu, 2018-12-20 at 12:05 +0000, Paul Durrant wrote: > > > -----Original Message----- > > > > > > The memory for the asynchronous ring and the synchronous channels > > > will > > > be allocated from domheap and mapped to the controlling domain > > > using the > > > foreignmemory_map_resource interface. Unlike the current > > > implementation, > > > the allocated pages are not part of the target DomU, so they will > > > not be > > > reclaimed when the vm_event domain is disabled. > > > > Why re-invent the wheel here? The ioreq infrastructure already does > > pretty much everything you need AFAICT. > > > > Paul > > > > Hi Paul, > > I'm still struggling to understand how the vm_event subsystem could be > integrated with an IOREQ server. > > An IOREQ server shares with the emulator 2 pages, one for ioreqs and > one for buffered_ioreqs. For vm_event we need to share also one or more > pages for the async ring and a few pages for the slotted synchronous > vm_events. > So, to my understanding, your idea to use the ioreq infrastructure for > vm_events is basically to replace the custom signalling (event channels > + ring / custom states) with ioreqs. Since the > vm_event_request/response structures are larger than 8 bytes, the > "data_is_ptr" flag should be used in conjunction with the addresses > (indexes) from the shared vm_event buffers. > > Is this the mechanism you had in mind? >
Yes, that's roughly what I hoped might be possible. If that is too cumbersome though then it should at least be feasible to mimic the ioreq code's page allocation functions and code up vm_event buffers as another type of mappable resource. Paul > Many thanks, > Petre _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
