Patrick Lauer wrote: [snip] >> Also it seems that you could have more than one of these privilidged >> osses installed at the same time sharing different parts of the >> hardware. >> > in theory yes, I don't know how well that is supported > [snip] only one os (dom0) access the hardware, it run at ring 0, on 32 bit machines there are 5 rings[#1], the other kernels (domU) run at ring 1, the userspace software always run at ring 5.
There are a set of cpu instruction that help using interrupts to virtualize the hardware access (also prior to vt). For tecnical reasons amd64 only kept ring 0 and 5 making it impossible for kernels like xen to continue working like before. Both 32 bit and 64 bit, intel or amd are developing a tecnology to help virtualization "vt" for intel "pacifica" for amd [#2][#3]. [#2] should explain the concept deepere and better, also for what vt does. Xen will take advantage from both I think. Don't know the others, so only these 2 €cents ;) [resnip] [#1] the number may differ from 5 due to my broken memory [#2] http://www.itarchitect.com/shared/article/showArticle.jhtml?articleId=172302134 [#3] http://www.google.it/search?q=amd+vt+virtualization -- [email protected] mailing list
