2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2006 Sam Leffler
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 * Support for redirecting console msgs to gdb. We register
31 * a pseudo console to hook cnputc and send stuff to the gdb
32 * port. The only trickiness here is buffering output so this
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
39 #include <sys/param.h>
40 #include <sys/systm.h>
43 #include <sys/kernel.h>
44 #include <sys/malloc.h>
45 #include <sys/reboot.h>
46 #include <sys/sysctl.h>
48 #include <machine/gdb_machdep.h>
49 #include <machine/kdb.h>
52 #include <gdb/gdb_int.h>
56 /* /2 for hex conversion, -6 for protocol glue */
57 char buf[GDB_BUFSZ/2 - 6];
60 static struct gdbcons state = { -1 };
62 static int gdbcons_enable = 0;
63 SYSCTL_INT(_debug, OID_AUTO, gdbcons, CTLFLAG_RWTUN, &gdbcons_enable,
64 0, "copy console messages to GDB");
67 gdb_cnprobe(struct consdev *cp)
69 sprintf(cp->cn_name, "gdb");
70 cp->cn_pri = CN_LOW; /* XXX no way to say "write only" */
74 gdb_cninit(struct consdev *cp)
76 struct gdbcons *c = &state;
78 /* setup tx buffer and callout */
79 if (c->npending == -1) {
81 callout_init(&c->flush, 1);
87 gdb_cnterm(struct consdev *cp)
92 gdb_cngrab(struct consdev *cp)
97 gdb_cnungrab(struct consdev *cp)
102 gdb_cngetc(struct consdev *cp)
110 const char *hex = "0123456789abcdef";
112 gdb_tx_char(hex[(c>>4)&0xf]);
113 gdb_tx_char(hex[(c>>0)&0xf]);
117 gdb_cnflush(void *arg)
119 struct gdbcons *gc = arg;
123 for (i = 0; i < gc->npending; i++)
124 gdb_tx_puthex(gc->buf[i]);
130 * This glop is to figure out when it's safe to use callouts
131 * to defer buffer flushing. There's probably a better way
132 * and/or an earlier point in the boot process when it's ok.
134 static int calloutok = 0;
136 oktousecallout(void *data __unused)
140 SYSINIT(gdbhack, SI_SUB_LAST, SI_ORDER_MIDDLE, oktousecallout, NULL);
143 gdb_cnputc(struct consdev *cp, int c)
147 if (gdbcons_enable && gdb_cur != NULL && gdb_listening) {
149 if (gc->npending != 0) {
151 * Cancel any pending callout and flush the
152 * buffer if there's no space for this byte.
155 callout_stop(&gc->flush);
156 if (gc->npending == sizeof(gc->buf))
159 gc->buf[gc->npending++] = c;
161 * Flush on end of line; this is especially helpful
162 * during boot when we don't have callouts to flush
163 * the buffer. Otherwise we defer flushing; a 1/4
169 callout_reset(&gc->flush, hz/4, gdb_cnflush, gc);
176 * Our console device only gets attached if the system is booted
177 * with RB_MULTIPLE set so gdb_init also calls us to attach the
178 * console so we're setup regardless.
183 gdb_cnprobe(&gdb_consdev);
184 gdb_cninit(&gdb_consdev);