From 983768431676f9ab8599a0b4813e1ca17af70838 Mon Sep 17 00:00:00 2001 From: Haozhong Zhang Date: Mon, 11 Dec 2017 15:28:04 +0800 Subject: hostmem-file: add "align" option When mmap(2) the backend files, QEMU uses the host page size (getpagesize(2)) by default as the alignment of mapping address. However, some backends may require alignments different than the page size. For example, mmap a device DAX (e.g., /dev/dax0.0) on Linux kernel 4.13 to an address, which is 4K-aligned but not 2M-aligned, fails with a kernel message like [617494.969768] dax dax0.0: qemu-system-x86: dax_mmap: fail, unaligned vma (0x7fa37c579000 - 0x7fa43c579000, 0x1fffff) Because there is no common approach to get such alignment requirement, we add the 'align' option to 'memory-backend-file', so that users or management utils, which have enough knowledge about the backend, can specify a proper alignment via this option. Signed-off-by: Haozhong Zhang Message-Id: <20171211072806.2812-2-haozhong.zhang@intel.com> Reviewed-by: Michael S. Tsirkin Reviewed-by: Stefan Hajnoczi [ehabkost: fixed typo, fixed error_setg() format string] Signed-off-by: Eduardo Habkost --- include/exec/memory.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/exec/memory.h') diff --git a/include/exec/memory.h b/include/exec/memory.h index a4cabdf44c..07c5d6d597 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -465,6 +465,8 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr, * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: size of the region. + * @align: alignment of the region base address; if 0, the default alignment + * (getpagesize()) will be used. * @share: %true if memory must be mmaped with the MAP_SHARED flag * @path: the path in which to allocate the RAM. * @errp: pointer to Error*, to store an error if it happens. @@ -476,6 +478,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, struct Object *owner, const char *name, uint64_t size, + uint64_t align, bool share, const char *path, Error **errp); -- cgit v1.2.3-55-g7522