sysbeep-keep-at-halt.patch -- NetBSD 11.0/x86: keep sysbeep0 attached at
halt, so "options BEEP_ONHALT" can sound (NetBSD PR kern/60735).  Needs
pcppi-keep-at-halt.patch as well.  Apply in usr/src with: patch -p0

Author: Royce Williams
License: the same terms as each NetBSD source file it modifies.

--- sys/arch/x86/isa/clock.c.orig
+++ sys/arch/x86/isa/clock.c
@@ -169,9 +169,20 @@
 void sysbeepattach(device_t, device_t, void *);
 int sysbeepdetach(device_t, int);
 
+/*
+ * SYSBEEP_KEEP_AT_HALT -- NOT DVF_DETACH_SHUTDOWN.  With that flag,
+ * config_detach_all() at arch/i386/i386/machdep.c:838 detaches sysbeep0
+ * during an ordinary "shutdown -h", sysbeepdetach() clears ppi_attached,
+ * and the BEEP_ONHALT block 47 lines later calls a sysbeep() that does
+ * nothing.  PR kern/60735; upstream x86/isa/clock.c rev 1.44 reverts rev
+ * 1.32, which is where the flag was added.
+ *
+ * NOT SUFFICIENT ALONE: see PCPPI_KEEP_AT_HALT in sys/dev/isa/pcppi.c,
+ * without which the beep sounds at an unprogrammed 18 Hz.
+ */
 CFATTACH_DECL3_NEW(sysbeep, 0,
     sysbeepmatch, sysbeepattach, sysbeepdetach, NULL, NULL, NULL,
-    DVF_DETACH_SHUTDOWN);
+    0);
 
 static int ppi_attached;
 static pcppi_tag_t ppicookie;