Re: [libvirt] Exposing mem-path in domain XML

----- Original Message ----- Looking at the examples, it seems like these automatically added memory-backend-file objects would always be generated in a consistent manner. As long as this is true, and these objects always end up with a consistent filenames, our integration components can assume the filenames in a consistent way. For instance, as long as every numa <cell> element which has memory defined generates a file named ram-node<numa_node_number>, we can handle that mapping within our integration components by parsing the XML and identifying the NUMA nodes with memory, and allocating an appropriate amount, with the correct filename. For our integration to work well for users, we need to allocate the external memory prior to qemu starting, so we can give descriptive error messages as part of our integration components. The directory based approach would require us to allocate external memory when the individual files are created or mmap'd in qemu. This may lead to a situation where there is insufficient external memory, leading to the failure happening within qemu, and a much more generic qemu unable to allocate memory error. With the external memory allocations and files being created and sized prior to qemu startup via our integration components called via the libvirt prepare hook, we can detect this situation during the libvirt hook, and return a more appropriate error message. --Zack