At the moment if the user asked for huge pages and there is no more huge pages, QEMU prints warning and falls back to the anonymous memory allocator which is quite easy not to notice. QEMU also does so even if the user specified -mem-prealloc and it seems wrong as the user specifically requested huge pages for the entire RAM but QEMU failed to do so and continued. On PPC64 this will produce a fragile guest as QEMU tells the guest via device-tree that it can use huge pages when it actually cannot.
This adds message+exit if RAM cannot be preallocated from huge pages. Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> --- exec.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/exec.c b/exec.c index 9ad0a4b..deb8279 100644 --- a/exec.c +++ b/exec.c @@ -1041,6 +1041,10 @@ static void *file_ram_alloc(RAMBlock *block, area = mmap(0, memory, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); if (area == MAP_FAILED) { + if (mem_prealloc) { + perror("file_ram_alloc: failed to preallocate RAM"); + exit(1); + } perror("file_ram_alloc: can't mmap RAM pages"); close(fd); return (NULL); -- 1.8.4.rc4