dtrace ioctls

[YAMAMOTO Takashi]

hi,

some dtrace ioctls, including DTRACEIOC_AGGSNAP, are defined as
the following.

        #define DTRACEIOC_AGGSNAP       _IOW('x',7,dtrace_bufdesc_t *)

and libdtrace has diffs like the following.

        #if defined(sun)
                if (dt_ioctl(dtp, DTRACEIOC_AGGSNAP, buf) == -1) {
        #else
                if (dt_ioctl(dtp, DTRACEIOC_AGGSNAP, &buf) == -1) {
        #endif

they seem weird to me.
why can't they be like the following?

        _IOW('x',7,dtrace_bufdesc_t)

YAMAMOTO Takashi