On Thu, Oct 20, 2016 at 02:27:06PM +0100, Daniel P. Berrange wrote: > 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. > > That works if you always want to expose the entire file, but if you > intentionally only want to expose a subset you would still want > to set a size (and possibly offset too) and avoid the truncation
In this case, if you don't want truncation at all you shouldn't need to set a size on the backend object. Then QEMU could simply use the size specified in the frontend config (i.e. from -numa and/or -m). -- Eduardo
