2 * Copyright (c) 2006 Sam Leffler
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 * Support for redirecting console msgs to gdb. We register
29 * a pseudo console to hook cnputc and send stuff to the gdb
30 * port. The only trickiness here is buffering output so this
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
37 #include <sys/param.h>
38 #include <sys/systm.h>
41 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/reboot.h>
44 #include <sys/sysctl.h>
46 #include <machine/gdb_machdep.h>
47 #include <machine/kdb.h>
50 #include <gdb/gdb_int.h>
54 /* /2 for hex conversion, -6 for protocol glue */
55 char buf[GDB_BUFSZ/2 - 6];
58 static struct gdbcons state = { -1 };
60 static int gdbcons_enable = 0;
61 SYSCTL_INT(_debug, OID_AUTO, gdbcons, CTLFLAG_RW, &gdbcons_enable,
62 0, "copy console messages to gdb");
63 TUNABLE_INT("debug.gdbcons", &gdbcons_enable);
66 gdb_cnprobe(struct consdev *cp)
68 sprintf(cp->cn_name, "gdb");
69 cp->cn_pri = CN_LOW; /* XXX no way to say "write only" */
73 gdb_cninit(struct consdev *cp)
75 struct gdbcons *c = &state;
77 /* setup tx buffer and callout */
78 if (c->npending == -1) {
80 callout_init(&c->flush, CALLOUT_MPSAFE);
86 gdb_cnterm(struct consdev *cp)
91 gdb_cngrab(struct consdev *cp)
96 gdb_cnungrab(struct consdev *cp)
101 gdb_cngetc(struct consdev *cp)
109 const char *hex = "0123456789abcdef";
111 gdb_tx_char(hex[(c>>4)&0xf]);
112 gdb_tx_char(hex[(c>>0)&0xf]);
116 gdb_cnflush(void *arg)
118 struct gdbcons *gc = arg;
122 for (i = 0; i < gc->npending; i++)
123 gdb_tx_puthex(gc->buf[i]);
129 * This glop is to figure out when it's safe to use callouts
130 * to defer buffer flushing. There's probably a better way
131 * and/or an earlier point in the boot process when it's ok.
133 static int calloutok = 0;
135 oktousecallout(void *data __unused)
139 SYSINIT(gdbhack, SI_SUB_LAST, SI_ORDER_MIDDLE, oktousecallout, NULL);
142 gdb_cnputc(struct consdev *cp, int c)
146 if (gdbcons_enable && gdb_cur != NULL && gdb_listening) {
148 if (gc->npending != 0) {
150 * Cancel any pending callout and flush the
151 * buffer if there's no space for this byte.
154 callout_stop(&gc->flush);
155 if (gc->npending == sizeof(gc->buf))
158 gc->buf[gc->npending++] = c;
160 * Flush on end of line; this is especially helpful
161 * during boot when we don't have callouts to flush
162 * the buffer. Otherwise we defer flushing; a 1/4
168 callout_reset(&gc->flush, hz/4, gdb_cnflush, gc);
175 * Our console device only gets attached if the system is booted
176 * with RB_MULTIPLE set so gdb_init also calls us to attach the
177 * console so we're setup regardless.
182 gdb_cnprobe(&gdb_consdev);
183 gdb_cninit(&gdb_consdev);