it is defined in linux asm/sockios.h since commit
ae40eb1ef30ab4120bd3c8b7e3da99ee53d27a23 (linux v2.6.22)
but was missing from musl by accident.
in musl the sockios macros are exposed in sys/ioctl.h together
with other ioctl requests instead of in sys/socket.h because of
namespace rules. (glibc has them in sys/socket.h under _GNU_SOURCE.)
all bits headers that were identical for a number of 'clean' archs are
moved to the new arch/generic tree. in addition, a few headers that
differed only cosmetically from the new generic version are removed.
additional deduplication may be possible in mman.h and in several
headers (limits.h, posix.h, stdint.h) that mostly depend on whether
the arch is 32- or 64-bit, but they are left alone for now because
greater gains are likely possible with more invasive changes to header
logic, which is beyond the scope of this commit.
this port assumes eabi calling conventions, eabi linux syscall
convention, and presence of the kernel helpers at 0xffff0f?0 needed
for threads support. otherwise it makes very few assumptions, and the
code should work even on armv4 without thumb support, as well as on
systems with thumb interworking. the bits headers declare this a
little endian system, but as far as i can tell the code should work
equally well on big endian.
some small details are probably broken; so far, testing has been
limited to qemu/aboriginal linux.
Szabolcs Nagy
Rich Felker