1This hierarchy supports Linux systems using the new
2asm-generic/unistd.h, which removes many familiar old syscalls.  For
3example, to implement open(), newer Linux architectures require glibc
4to invoke the __NR_openat syscall with AT_FDCWD.  This hierarchy
5provides all those implementations.
6
7It also provides support for 32-bit platforms using the 64-bit kernel
8syscall APIs, as the 32-bit ones are no longer provided.  Note that
9newer ILP32 environments (x32 or AArch64:ILP32, for example) are
10converting to use more 64-bit types in kernel syscalls, so that aspect
11of this support is in more flux as of this writing.
12