[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Essay on an important Xen decision (long)
On Tue, 2006-01-10 at 16:39 -0800, Magenheimer, Dan (HP Labs Fort Collins) wrote: > > So ia64 dom0 physical 0 is machine 0? Where does Xen live in machine > > space? > > > > PowerPC exception handlers are architecturally hardcoded to the first > > couple pages of memory, so Xen needs to live there. Linux > > expects it is > > booting at 0 of course, so dom0 runs in an offset physical address > > space. > > On ia64, Xen (and Linux when booting natively) is relocatable. > Machine address 0 is not special on ia64 like it is on PowerPC. Right, so P==M for dom0 (or any domain) will not work on PowerPC. > Per the previous exchange with Anthony, there are many advantages > to being able to move memory around invisibly to domains, which > is easy with VP and much harder with P2M. The current debate on > Xen/ia64 is just for domain0 but it could expand... As far as I can see, dom0 must be aware of the machine address space, so that means P2M for PowerPC. dom0 is a special case: do you really need to worry about migrating dom0, or memory compacting with other domains? As for the question of domU being VP or P2M, I see no reason it shouldn't be VP. IO-capable domUs (driver domains) could be VP with proper IOMMU support. The PowerPC PAPR and Xen/ia64 implementations demonstrate that this works... -- Hollis Blanchard IBM Linux Technology Center _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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