libxl requires the memory sizes to be rounded to 1MiB increments. Attempting to start a domain that violates this requirement will fail with the marginally helpful error 2018-02-22 01:55:32.921+0000: xc: panic: xc_dom_boot.c:141: xc_dom_boot_mem_init: can't allocate low memory for domain: Out of memory 2018-02-22 01:55:32.921+0000: libxl: libxl_dom.c:671:libxl__build_dom: xc_dom_boot_mem_init failed: No such file or directory Round the maximum and current memory values to the next 1MiB increment when generating the libxl_domain_config object. Signed-off-by: Jim Fehlig <jfehlig(a)suse.com&gt; --- V2: Set rounded memory values in virDomainDef object so they are correctly reflected in the live config. src/libxl/libxl_conf.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c index 57cb4c0ad..d074edc9c 100644 --- a/src/libxl/libxl_conf.c +++ b/src/libxl/libxl_conf.c @@ -367,6 +367,10 @@ libxlMakeDomBuildInfo(virDomainDefPtr def, } b_info->sched_params.weight = 1000; + /* Xen requires the memory sizes to be rounded to 1MiB increments */ + virDomainDefSetMemoryTotal(def, + VIR_ROUND_UP(virDomainDefGetMemoryInitial(def), 1024)); + def->mem.cur_balloon = VIR_ROUND_UP(def->mem.cur_balloon, 1024); b_info->max_memkb = virDomainDefGetMemoryInitial(def); b_info->target_memkb = def->mem.cur_balloon; if (hvm) { -- 2.16.1