From bf56e64a4c564cd31300ccea8dbaf84670800e6a Mon Sep 17 00:00:00 2001
From: Ian Lepore <ian@FreeBSD.org>
Date: Sun, 25 Feb 2018 18:42:59 +0000
Subject: [PATCH] Add support for booting into kdb on arm platforms when the
 RB_KDB is set (using "boot -d" at the loader propmt or setting boot_ddb in
 loader.conf).

Submitted by:	Thomas Skibo <thomasskibo@yahoo.com>
Differential Revision:	https://reviews.freebsd.org/D14428
---
 sys/arm/arm/machdep.c      | 15 +++++++++++++--
 sys/arm/arm/machdep_boot.c |  5 +++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/sys/arm/arm/machdep.c b/sys/arm/arm/machdep.c
index 491850130ba7..1d65b12b5a63 100644
--- a/sys/arm/arm/machdep.c
+++ b/sys/arm/arm/machdep.c
@@ -66,6 +66,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/kernel.h>
 #include <sys/linker.h>
 #include <sys/msgbuf.h>
+#include <sys/reboot.h>
 #include <sys/rwlock.h>
 #include <sys/sched.h>
 #include <sys/syscallsubr.h>
@@ -785,6 +786,16 @@ set_stackptrs(int cpu)
 }
 #endif
 
+static void
+arm_kdb_init(void)
+{
+
+	kdb_init();
+#ifdef KDB
+	if (boothowto & RB_KDB)
+		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
+#endif
+}
 
 #ifdef FDT
 #if __ARM_ARCH < 6
@@ -1054,7 +1065,7 @@ initarm(struct arm_boot_params *abp)
 
 	init_param2(physmem);
 	dbg_monitor_init();
-	kdb_init();
+	arm_kdb_init();
 
 	return ((void *)(kernelstack.pv_va + USPACE_SVC_STACK_TOP -
 	    sizeof(struct pcb)));
@@ -1263,7 +1274,7 @@ initarm(struct arm_boot_params *abp)
 	/* Init message buffer. */
 	msgbufinit(msgbufp, msgbufsize);
 	dbg_monitor_init();
-	kdb_init();
+	arm_kdb_init();
 	/* Apply possible BP hardening. */
 	cpuinfo_init_bp_hardening();
 	return ((void *)STACKALIGN(thread0.td_pcb));
diff --git a/sys/arm/arm/machdep_boot.c b/sys/arm/arm/machdep_boot.c
index adb15f427be3..eb53967527e0 100644
--- a/sys/arm/arm/machdep_boot.c
+++ b/sys/arm/arm/machdep_boot.c
@@ -27,6 +27,7 @@
  */
 
 #include "opt_platform.h"
+#include "opt_ddb.h"
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
@@ -57,6 +58,10 @@ __FBSDID("$FreeBSD$");
 #include <sys/efi.h>
 #endif
 
+#ifdef DDB
+#include <ddb/ddb.h>
+#endif
+
 #ifdef DEBUG
 #define	debugf(fmt, args...) printf(fmt, ##args)
 #else