On Mon, Dec 11, 2017 at 03:28:04PM +0800, Haozhong Zhang wrote: > 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 <haozhong.zh...@intel.com> > --- > backends/hostmem-file.c | 41 ++++++++++++++++++++++++++++++++++++++++- > docs/nvdimm.txt | 16 ++++++++++++++++ > exec.c | 8 +++++++- > include/exec/memory.h | 3 +++ > memory.c | 2 ++ > numa.c | 2 +- > qemu-options.hx | 9 ++++++++- > 7 files changed, 77 insertions(+), 4 deletions(-)
Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
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