Allow the appliance / root filesystem to be placed on a virtual NVDIMM and accessed directly by the guest kernel (DAX). This requires corresponding changes in supermin. --- src/launch-direct.c | 66 ++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 53 insertions(+), 13 deletions(-) diff --git a/src/launch-direct.c b/src/launch-direct.c index a6f06ee..daeff67 100644 --- a/src/launch-direct.c +++ b/src/launch-direct.c @@ -235,6 +235,7 @@ launch_direct (guestfs_h *g, void *datav, const char *arg) struct hv_param *hp; bool has_kvm; int force_tcg; + bool dax; const char *cpu_model; /* At present you must add drives before starting the appliance. In @@ -374,15 +375,29 @@ launch_direct (guestfs_h *g, void *datav, const char *arg) warning (g, "qemu debugging is enabled, connect gdb to tcp::1234 to begin"); } + /* Can we use DAX? */ +#ifdef __x86_64__ + dax = guestfs_int_version_ge (&data->qemu_version, 2, 6, 0) && + guestfs_int_qemu_supports_device (g, data->qemu_data, "nvdimm"); +#else + dax = false; +#endif + ADD_CMDLINE ("-machine"); ADD_CMDLINE_PRINTF ( #ifdef MACHINE_TYPE MACHINE_TYPE "," + "%s" +#elif __x86_64__ + "pc,%s" +#else + "%s" #endif #ifdef __aarch64__ "gic-version=host," #endif "accel=%s", + dax ? "nvdimm," : "", !force_tcg ? "kvm:tcg" : "tcg"); cpu_model = guestfs_int_get_cpu_model (has_kvm && !force_tcg); @@ -397,7 +412,10 @@ launch_direct (guestfs_h *g, void *datav, const char *arg) } ADD_CMDLINE ("-m"); - ADD_CMDLINE_PRINTF ("%d", g->memsize); + if (dax) + ADD_CMDLINE_PRINTF ("%d,maxmem=32G,slots=32", g->memsize); + else + ADD_CMDLINE_PRINTF ("%d", g->memsize); /* Force exit instead of reboot on panic */ ADD_CMDLINE ("-no-reboot"); @@ -551,21 +569,43 @@ launch_direct (guestfs_h *g, void *datav, const char *arg) /* Add the ext2 appliance drive (after all the drives). */ if (has_appliance_drive) { - ADD_CMDLINE ("-drive"); - ADD_CMDLINE_PRINTF ("file=%s,snapshot=on,id=appliance," - "cache=unsafe,if=none,format=raw", - appliance); + if (dax) { + struct stat statbuf; - if (virtio_scsi) { - ADD_CMDLINE ("-device"); - ADD_CMDLINE ("scsi-hd,drive=appliance"); - } - else { + if (stat (appliance, &statbuf) == -1) { + perrorf (g, "stat: %s", appliance); + goto cleanup0; + } + + ADD_CMDLINE ("-object"); + /* share=off corresponds to mmap MAP_PRIVATE inside qemu, so + * this should not affect the underlying file. IOW parallel + * access should be fine. + */ + ADD_CMDLINE_PRINTF ("memory-backend-file,id=mem1,share=off," + "mem-path=%s,size=%" PRIu64 "b", + appliance, (uint64_t) statbuf.st_size); ADD_CMDLINE ("-device"); - ADD_CMDLINE (VIRTIO_BLK ",drive=appliance"); - } + ADD_CMDLINE ("nvdimm,memdev=mem1,id=nv1"); - appliance_dev = make_appliance_dev (g, virtio_scsi); + appliance_dev = safe_strdup (g, "/dev/pmem0"); + } else { + ADD_CMDLINE ("-drive"); + ADD_CMDLINE_PRINTF ("file=%s,snapshot=on,id=appliance," + "cache=unsafe,if=none,format=raw", + appliance); + + if (virtio_scsi) { + ADD_CMDLINE ("-device"); + ADD_CMDLINE ("scsi-hd,drive=appliance"); + } + else { + ADD_CMDLINE ("-device"); + ADD_CMDLINE (VIRTIO_BLK ",drive=appliance"); + } + + appliance_dev = make_appliance_dev (g, virtio_scsi); + } } /* Create the virtio serial bus. */ -- 2.7.4