trap.c: Why do we save tf_edx in sysmsg_fds[1]?

["David P. Reese, Jr." <daver@xxxxxxxxxxxx>]

In syscall2(), why do we save tf_edx in sysmsg_fds[1] before calling the
actual syscall?  sendsys2() doesn't look like it saves this register
value either.

Grep'ing sys/kern/* doesn't tell me much.

-- 
   David P. Reese, Jr.                                     daver@xxxxxxxxxxxx
                                               http://www.gomerbud.com/daver/