On Sun, Jan 14, 2018 at 11:01:45AM +0200, Marcel Apfelbaum wrote: > +5. Limitations > +==============
Limitations are fine but need to cause init failures since users don't poke in the internal documentation. > +- The device obviously is limited by the Guest Linux Driver features > implementation > + of the VMware device API. > +- Memory registration mechanism requires mremap for every page in the buffer > in order > + to map it to a contiguous virtual address range. Since this is not the > data path > + it should not matter much. Depends on the size of the region I guess. Did you try this with several gigabytes of memory? If we are talking seconds of downtime, it's worth documenting so people aren't surprised. Alternatively, limit the max size of MR? > +- The device requires target page size to be the same as the host page size. Pls add code to fail init when this is not the case. > +- QEMU cannot map guest RAM from a file descriptor if a pvrdma device is > attached, > + so it can't work with huge pages. The limitation will be addressed in the > future, > + however QEMU allocates Guest RAM with MADV_HUGEPAGE so if there are enough > huge > + pages available, QEMU will use them. Same here. > +- As previously stated, migration is not supported yet, however with some > hardware > + support can be done. I don't see a migration blocker. -- MST
