Hi, I wanted to test the mapped_file_source iostream device. My code is working well with a normal file_source device and files >= 6GB. When I change the constructor to a mapped_file_source, it works still well for smaller files (e.g. 150MB), but for files > 2GB I get (tested with 2.5GB): exception occured: failed getting file size: Value too large for defined data type And for files > 4GB (tested with 6GB) I get: exception occured: failed opening file: Bad file descriptor My constructor is as follows: using namespace boost::iostreams; typedef stream<mapped_file_source> mmStream; mmStream* mmistream = new mmStream(); mmistream->open(mapped_file_source(fileName)); I've tested against boost 1.44 and a 32bit linux (Ubuntu 10.04). Are these general mmap problems, or am I missing some flags for mapped_file_source? Best regards, Heiko