[Libguestfs] [nbdkit] [filter/nozero] large binary size with GCC 9

Hi all, It seems GCC 9 does not put read-only zero-initialized variables into the BSS section anymore; instead it is put into RODATA. (See the thread at [0], especially [1]) In filter/nozero a 64M large, static, zeroed, read-only array is declared. The new behavior of GCC puts this array as-is into the binary inflating the size by a factor of around 10000. (Clang 8 and older GCCs work "correctly") It would be possible to remove the "const" qualifier or use some compiler attribute trickery to get the previous behavior back. Thanks, Thomas [0] https://gcc.gnu.org/ml/gcc/2019-04/msg00034.html [1] https://gcc.gnu.org/ml/gcc/2019-04/msg00049.html