Hi Alan, Erik and Hirofumi and the rest, I want to inform you of my success. So first of all thanks for your help!
Assuring, that the buffer is aligned according 4k (pagesize = getpagesize() and multiple of sectorsize = blockdev --getss) using memalign or posix_memalign, did the job. Thanks a lot. A very nice feature. The compiler option -D_GNU_SOURCE helped also to avoid including asm-header of fcntl.h. bye Hubi
pgpGqEtzZJURL.pgp
Description: PGP signature
