On Thu, Oct 20, 2016 at 02:34:12PM +0200, Igor Mammedov wrote: > On Thu, 20 Oct 2016 14:13:01 +0800 > Haozhong Zhang <haozhong.zh...@intel.com> wrote: > > > If a file is used as the backend of memory-backend-file and its size is > > not identical to the property 'size', the file will be truncated. For a > > file used as the backend of vNVDIMM, its data is expected to be > > persistent and the truncation may corrupt the existing data. > I wonder if it's possible just skip 'size' property in your case instead > 'notrunc' property. That way if size is not present one'd get actual size > using get_file_size() and set 'size' to it? > And if 'size' is provided and 'size' != file_size then error out.
I think it is valid to start with a zero-size file and then let QEMU extend it. But I agree we should: 1) make 'size' optional as you suggested; 2) never truncate the file to a smaller size. -- Eduardo
