On 24/05/22 10:58AM, Miklos Szeredi wrote: > On Wed, 22 May 2024 at 04:05, John Groves <John@xxxxxxxxxx> wrote: > > I'm happy to help with that if you care - ping me if so; getting a VM running > > in EFI mode is not necessary if you reserve the dax memory via memmap=, or > > via libvirt xml. > > Could you please give an example? > > I use a raw qemu command line with a -kernel option and a root fs > image (not a disk image with a bootloader). That's not the way I'm running VMs, but... I presume you know how to add kernel command line arguments to VMs that you run this way? - memmap=<size>!<hpa_offset> will reserve a pretend pmem device at <hpa_offset> - memmap=<size>$<hpa_offset> will reserve a pretend dax device at <hpa_offset> Both of the above will work regardless of whether the VM is in EFI mode. The '$' is harder to escape through grub; and the pmem device can be converted to devdax via 'ndctl reconfigure-device --mode=devdax...'. A dax device would likely also need to be put in devdax mode (as the default seems to be system-ram mode). Incomplete documentation (that you have probably already seen) is at [1] I can dig deeper if needed. Otherwise the feedback in this thread makes sense to me and I'm planning to start hacking on famfs patches Thursday. Watch this space ;) Regards, John [1] https://github.com/cxl-micron-reskit/famfs/blob/master/markdown/vm-configuration.md
