[libvirt] Error when creating VM with persistent memory

[Dan Williams]

On Wed, Sep 4, 2019 at 12:56 AM Seema Pandit <pan.blr.17 at gmail.com> wrote:
>
> Actually there is still some issue around this. When trying to start another VM, so using even more pmem, there is a different issue now. Error copied below.
>
> []# virsh start manual_clone
>
> error: Failed to start domain manual_clone
>
> error: internal error: qemu unexpectedly closed the monitor: ftruncate: Invalid argument
>
> 2019-09-03T21:28:41.031924Z qemu-system-x86_64: -object memory-backend-file,id=memnvdimm0,prealloc=yes,mem-path=/dev/dax1.1,share=yes,size=73014444032: os_mem_prealloc: Insufficient free host memory pages available to allocate guest RAM

/dev/dax instances do not support the ftruncate syscall, and
device-dax instances are already fully allocated by definition. The
prealloc option is simply invalid for /dev/dax targets.