On 09/15/2009 04:03 PM, Gregory Haskins wrote: > >> In this case the x86 is the owner and the ppc boards use translated >> access. Just switch drivers and device and it falls into place. >> >> > You could switch vbus roles as well, I suppose.
Right, there's not real difference in this regard. > Another potential > option is that he can stop mapping host memory on the guest so that it > follows the more traditional model. As a bus-master device, the ppc > boards should have access to any host memory at least in the GFP_DMA > range, which would include all relevant pointers here. > > I digress: I was primarily addressing the concern that Ira would need > to manage the "host" side of the link using hvas mapped from userspace > (even if host side is the ppc boards). vbus abstracts that access so as > to allow something other than userspace/hva mappings. OTOH, having each > ppc board run a userspace app to do the mapping on its behalf and feed > it to vhost is probably not a huge deal either. Where vhost might > really fall apart is when any assumptions about pageable memory occur, > if any. > Why? vhost will call get_user_pages() or copy_*_user() which ought to do the right thing. > As an aside: a bigger issue is that, iiuc, Ira wants more than a single > ethernet channel in his design (multiple ethernets, consoles, etc). A > vhost solution in this environment is incomplete. > Why? Instantiate as many vhost-nets as needed. > Note that Ira's architecture highlights that vbus's explicit management > interface is more valuable here than it is in KVM, since KVM already has > its own management interface via QEMU. > vhost-net and vbus both need management, vhost-net via ioctls and vbus via configfs. The only difference is the implementation. vhost-net leaves much more to userspace, that's the main difference. -- error compiling committee.c: too many arguments to function _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/virtualization
