Apply by doing:
       cd /usr/src
       patch -p0 < 018_gdt.patch

And then rebuild your kernel.

Index: sys/dev/ic/gdt_common.c
===================================================================
RCS file: /cvs/src/sys/dev/ic/gdt_common.c,v
retrieving revision 1.26
retrieving revision 1.26.2.1
diff -u -p -r1.26 -r1.26.2.1
--- sys/dev/ic/gdt_common.c     28 Jun 2003 23:56:40 -0000      1.26
+++ sys/dev/ic/gdt_common.c     30 Apr 2004 23:30:40 -0000      1.26.2.1
@@ -58,7 +58,7 @@ int gdt_maxcmds = GDT_MAXCMDS;
#endif

#define GDT_DRIVER_VERSION 1
-#define GDT_DRIVER_SUBVERSION 1
+#define GDT_DRIVER_SUBVERSION 2

int    gdt_async_event(struct gdt_softc *, int);
void   gdt_chain(struct gdt_softc *);
@@ -176,19 +176,6 @@ gdt_attach(gdt)
               return (1);
       }

-       if (!gdt_internal_cmd(gdt, GDT_CACHESERVICE, GDT_MOUNT, 0xffff, 1,
-           0)) {
-               printf("cache service mount error %d\n",
-                   gdt->sc_status);
-               return (1);
-       }
-
-       if (!gdt_internal_cmd(gdt, GDT_CACHESERVICE, GDT_INIT, GDT_LINUX_OS, 0,
-           0)) {
-               printf("cache service post-mount initialization error %d\n",
-                   gdt->sc_status);
-               return (1);
-       }
       cdev_cnt = (u_int16_t)gdt->sc_info;

       /* Detect number of busses */