I've been having some trouble lately with getting my i386 systems with
serial consoles to reboot after halt.
I've made the following changes in an attempt to see if XON/XOFF flow
control might be the problem and to provide further diagnostics and
operator information.
The following demonstrates what I see happening:
historically# halt -q
syncing disks... 6 done
unmounting file systems...
unmounting /kern (kernfs)...ok,
unmounting /tmp (mfs:156)...ok,
unmounting / (/dev/wd0a)...ok, done
The operating system has halted.
Please press any key to reboot.
[halt sent]
Cannot read from the console, calling the HLT instruction.
RESET or power cycle the system to reboot.
The "[halt sent]" is from conserver, after having pressed many keys.
Index: sys/arch/i386/i386/machdep.c
===================================================================
RCS file: /cvs/master/m-NetBSD/main/src/sys/arch/i386/i386/machdep.c,v
retrieving revision 1.632
diff -u -r1.632 machdep.c
--- sys/arch/i386/i386/machdep.c 29 Apr 2008 15:27:08 -0000 1.632
+++ sys/arch/i386/i386/machdep.c 30 Apr 2008 12:43:24 -0000
@@ -848,6 +848,7 @@
void
cpu_reboot(int howto, char *bootstr)
{
+ int keyval = 0;
if (cold) {
howto |= RB_HALT;
@@ -855,6 +856,10 @@
}
boothowto = howto;
+ /*
+ * XXX this bit, except for the "cold" check above, should be MI --
+ * i.e. back in kern/kern_xxx.c:sys_reboot()
+ */
if ((howto & RB_NOSYNC) == 0 && waittime < 0) {
waittime = 0;
vfs_shutdown();
@@ -914,11 +919,10 @@
}
if (howto & RB_HALT) {
- printf("\n");
- printf("The operating system has halted.\n");
- printf("Please press any key to reboot.\n\n");
+ printf("\nThe operating system has halted.\n"
+ "Please press any key to reboot.\n\n");
-#ifdef BEEP_ONHALT
+#ifdef BEEP_ONHALT /* XXX could be: defined(BEEP_ONHALT_COUNT) &&
(BEEP_ONHALT_COUNT > 0) */
{
int c;
for (c = BEEP_ONHALT_COUNT; c > 0; c--) {
@@ -931,21 +935,58 @@
}
#endif
- cnpollc(1); /* for proper keyboard command handling */
- if (cngetc() == 0) {
- /* no console attached, so just hlt */
- for(;;) {
- x86_hlt();
+ cnpollc(1); /* for proper keyboard command handling without
+ * interrupts */
+ /*
+ * ACK!!! The line discipline does _NOT_ get used from within
+ * the kernel for console I/O (though it probably should be).
+ *
+ * If any output above went out too fast for the device
+ * connected to a serial console then we'll read a <CTRL-S>
+ * here, and/or perhaps a <CTRL-Q>, and we'll just have to
+ * ignore them.
+ */
+#define ASCII_XON 0x11
+#define ASCII_XOFF 0x13
+ while (keyval != ASCII_XOFF && keyval != ASCII_XON) {
+ if (cngetc() == 0) {
+ /*
+ * no console attached, or perhaps a BREAK
+ * condition caused a read error, so just
+ * invoke the HLT instruction and wait for the
+ * operator to push the reset (or power)
+ * button.
+ */
+ printf("\nCannot read from the console, calling
the HLT instruction.\n\n");
+ printf("RESET or power cycle the system to
reboot.\n\n");
+ for(;;) {
+ x86_hlt();
+ }
+ /*NOTREACHED*/
}
+#ifdef DEBUG
+ else if (keyval == ASCII_XOFF && keyval != ASCII_XON) {
+ printf("(ignoring flow control char (0x%x)\n",
keyval);
+ /* XXX even this could trigger another XOFF,
sigh... */
+ }
+#endif
}
cnpollc(0);
}
+#ifdef DEBUG
+ if (keyval)
+ printf("(read key value 0x%x)\n\n", keyval);
+#endif
printf("rebooting...\n");
if (cpureset_delay > 0)
delay(cpureset_delay * 1000);
cpu_reset();
- for(;;) ;
+ printf("cpu_reset() returned, waiting for hardware to reset or be
reset...\n\n");
+
+ for(;;) {
+ x86_hlt();
+ }
/*NOTREACHED*/
}
--
Greg A. Woods
Planix, Inc.
<woods%planix.com@localhost> +1 416 489-5852 x122 http://www.planix.com/
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