In article [ref] (at Thu, 22 Jun 2006 23:14:07 -0700 (PDT)), David Miller [off-list ref] says:

From: YOSHIFUJI Hideaki <redacted>
Date: Fri, 23 Jun 2006 15:12:44 +0900 (JST)

quoted

We do not waste syscall entries; we can probably use socketcall
for sys_aio_recv, sys_aio_send (and maybe, sys_aio_sendfile).

socketcall is deprecated and some architectures do not even
have a slot for it in their system call tables, one example
is x86_64

Ah, okay.  Thanks.

--yoshfuji