On Fri, Jul 08, 2011 at 07:28:39PM -0400, Doug Lytle wrote: > Can you say a Virtualized Asterisk with a PRI card! > > http://www.phoronix.com/scan.php?page=news_item&px=OTY0OQ
I'm not sure this is relevant to your everyday PRI card. Simple pass-through of PCI is rather simple to implement. It has been implemented for quite some time in e.g. qemu, IIRC. But there's one important feature that is tricky to implement: DMA. DMA allows a PCI card to basically free access to the memory of the system, without the CPU getting in the middle. Emulating this with the host CPU in the middle will work, but is exepnsive. But the host does not want to give the guest free access to the host's memory. The solution: IOMMU: http://en.wikipedia.org/wiki/Iommu . The CPU of the system has a Memory Management Unit (MMU) that maps virtual address spaces to processes. Likewise we know prevent the IO card from seeing physical addresses. Rather, it sees virtual addresses mapped by the IOMMU. Just like the operating system maps addresses for processes, the hypervisor maps address ranger to IO cards. See also the link in that Phoronix article: http://www.ibm.com/developerworks/linux/library/l-pci-passthrough/ I'm not well familiar with the relevant hardware, but I believe that not only not every CPU supports this, but many (most?) PCI cards don't support IOMMU. -- Tzafrir Cohen icq#16849755 jabber:[email protected] +972-50-7952406 mailto:[email protected] http://www.xorcom.com iax:[email protected]/tzafrir -- _____________________________________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
