fix root detection on evbarm when raid is involved

there are several problems solved in this change:
- lots of work was re-done when we already have determined the
  device booted from, so several new early returns introduced
  if booted_device has been set
- due to the lack of cpu_bootconf(), raidframe softroot would
  override "root=xxx" on the boot command line
- in the new cpu_bootconf(), switch the order of the platform
  boot-config with the set_root_device() call.  this avoids a
  problem where "root=xxx" is checked after automated methods,
  and is thus ignored.
- in fdt_detect_root_device(), remove the code to add "root=xxx""
  string to the boot_args[] that would be later parsed by the
  set_root_device() call, and simply set booted_device and, for
  mbr installs, booted_partition directly.  also, try to load
  the partition table, and if this partition is type MSDOS, choose
  partition 0 instead - for a normal/old mbr install, this means
  booting the msdos partition kernel will choose the ffs partition
  for root instead.   also, for any successful call, perform an
  early return.
- define __HAVE_CPU_BOOTCONF so early boot calls cpu_bootconf().


tested on:
- rockpro64 booting from emmc, sata
- rockpro64 loading kernel from msdos partition
- rockpro64 booting from network (fails to auto-detect, with or
  without this change.)
- quartz64 booting from nvme


Index: arch/evbarm/evbarm/autoconf.c
===================================================================
RCS file: /cvsroot/src/sys/arch/evbarm/evbarm/autoconf.c,v
retrieving revision 1.23
diff -p -u -r1.23 autoconf.c
--- arch/evbarm/evbarm/autoconf.c	19 Dec 2020 21:54:00 -0000	1.23
+++ arch/evbarm/evbarm/autoconf.c	27 Jan 2023 07:22:31 -0000
@@ -108,6 +108,9 @@ set_root_device(void)
 	char *ptr, *end, *buf;
 	size_t len;
 
+	if (booted_device)
+		return;
+
 	if (boot_args == NULL)
 		return;
 
@@ -118,7 +121,7 @@ set_root_device(void)
 		return;
 
 	/* NUL-terminate string, get_bootconf_option doesn't */
-	for (end=ptr; *end != '\0'; ++end) {
+	for (end = ptr; *end != '\0'; ++end) {
 		if (*end == ' ' || *end == '\t') {
 			break;
 		}
@@ -144,16 +147,25 @@ set_root_device(void)
 #endif
 
 /*
- * Set up the root device from the boot args
+ * Set up the root device from the boot args.
+ *
+ * cpu_bootconf() is called before RAIDframe root detection,
+ * and cpu_rootconf() is called after.
  */
 void
-cpu_rootconf(void)
+cpu_bootconf(void)
 {
 #ifndef MEMORY_DISK_IS_ROOT
+	set_root_device();
 	if (evbarm_cpu_rootconf)
 		(*evbarm_cpu_rootconf)();
-	set_root_device();
 #endif
+}
+
+void
+cpu_rootconf(void)
+{
+	cpu_bootconf();
 	aprint_normal("boot device: %s\n",
 	    booted_device != NULL ? device_xname(booted_device) : "<unknown>");
 	rootconf();
Index: arch/evbarm/fdt/fdt_machdep.c
===================================================================
RCS file: /cvsroot/src/sys/arch/evbarm/fdt/fdt_machdep.c,v
retrieving revision 1.99
diff -p -u -r1.99 fdt_machdep.c
--- arch/evbarm/fdt/fdt_machdep.c	4 Nov 2022 10:51:17 -0000	1.99
+++ arch/evbarm/fdt/fdt_machdep.c	27 Jan 2023 07:22:31 -0000
@@ -738,19 +738,42 @@ delay(u_int us)
 	plat->ap_delay(us);
 }
 
+/*
+ * Check if we're booted from an MSDOS partition, look for a
+ * reasonable boot partition on this disk that is large enough.
+ */
+static int
+choose_root_part(struct disklabel *label, int part)
+{
+	/* Arbitrary 100 MiB size or root. */
+	const uint32_t minroot = 1024 * 1024 * 100;
+
+	/* return part if not msdos */
+	if (label->d_partitions[part].p_fstype != FS_MSDOS)
+		return part;
+
+	for (int n = 0; n < label->d_npartitions; n++) {
+		if (label->d_partitions[n].p_size >= minroot &&
+		    (label->d_partitions[n].p_fstype == FS_BSDFFS ||
+		     label->d_partitions[n].p_fstype == FS_BSDLFS ||
+		     label->d_partitions[n].p_fstype == FS_ISO9660 ||
+		     label->d_partitions[n].p_fstype == FS_APPLEUFS ||
+		     label->d_partitions[n].p_fstype == FS_EX2FS ||
+		     label->d_partitions[n].p_fstype == FS_RAID))
+			return n;
+	}
+
+	/* Nothing else, try it anyway. */
+	return part;
+}
+
 static void
 fdt_detect_root_device(device_t dev)
 {
-	struct mbr_sector mbr;
-	uint8_t buf[DEV_BSIZE];
-	uint8_t hash[16];
-	const uint8_t *rhash;
-	char rootarg[64];
-	struct vnode *vp;
-	MD5_CTX md5ctx;
 	int error, len;
-	size_t resid;
-	u_int part;
+
+	if (booted_device)
+		return;
 
 	const int chosen = OF_finddevice("/chosen");
 	if (chosen < 0)
@@ -758,6 +781,15 @@ fdt_detect_root_device(device_t dev)
 
 	if (of_hasprop(chosen, "netbsd,mbr") &&
 	    of_hasprop(chosen, "netbsd,partition")) {
+		struct disklabel label;
+		struct mbr_sector mbr;
+		uint8_t buf[DEV_BSIZE];
+		uint8_t hash[16];
+		const uint8_t *rhash;
+		struct vnode *vp;
+		MD5_CTX md5ctx;
+		size_t resid;
+		u_int part;
 
 		/*
 		 * The bootloader has passed in a partition index and MD5 hash
@@ -776,7 +808,13 @@ fdt_detect_root_device(device_t dev)
 			return;
 		error = vn_rdwr(UIO_READ, vp, buf, sizeof(buf), 0, UIO_SYSSPACE,
 		    IO_NODELOCKED, NOCRED, &resid, NULL);
+		if (error == 0) {
+			VOP_UNLOCK(vp);
+			error = VOP_IOCTL(vp, DIOCGDINFO, &label, FREAD, NOCRED);
+			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+		}
 		VOP_CLOSE(vp, FREAD, NOCRED);
+
 		vput(vp);
 
 		if (error != 0)
@@ -787,22 +825,27 @@ fdt_detect_root_device(device_t dev)
 		MD5Update(&md5ctx, (void *)&mbr, sizeof(mbr));
 		MD5Final(hash, &md5ctx);
 
-		if (memcmp(rhash, hash, 16) != 0)
-			return;
+		if (memcmp(rhash, hash, 16) == 0) {
+			booted_device = dev;
+			booted_partition = choose_root_part(&label, part);
+
+			if (part != booted_partition)
+				printf("boot: %s: using partition 0 instead of "
+				       "MSDOS partition %u\n",
+				       device_xname(dev), part);
+		}
 
-		snprintf(rootarg, sizeof(rootarg), " root=%s%c", device_xname(dev), part + 'a');
-		strcat(boot_args, rootarg);
+		return;
 	}
 
 	if (of_hasprop(chosen, "netbsd,gpt-guid")) {
-		char guidbuf[UUID_STR_LEN];
-		const struct uuid *guid = fdtbus_get_prop(chosen, "netbsd,gpt-guid", &len);
-		if (guid == NULL || len != 16)
-			return;
+		const struct uuid *guid =
+		    fdtbus_get_prop(chosen, "netbsd,gpt-guid", &len);
+
+		if (guid != NULL && len == 16)
+			booted_device = dev;
 
-		uuid_snprintf(guidbuf, sizeof(guidbuf), guid);
-		snprintf(rootarg, sizeof(rootarg), " root=wedge:%s", guidbuf);
-		strcat(boot_args, rootarg);
+		return;
 	}
 
 	if (of_hasprop(chosen, "netbsd,gpt-label")) {
@@ -813,14 +856,20 @@ fdt_detect_root_device(device_t dev)
 		device_t dv = dkwedge_find_by_wname(label);
 		if (dv != NULL)
 			booted_device = dv;
+
+		return;
 	}
 
 	if (of_hasprop(chosen, "netbsd,booted-mac-address")) {
-		const uint8_t *macaddr = fdtbus_get_prop(chosen, "netbsd,booted-mac-address", &len);
+		const uint8_t *macaddr =
+		    fdtbus_get_prop(chosen, "netbsd,booted-mac-address", &len);
+		struct ifnet *ifp;
+		int s;
+
 		if (macaddr == NULL || len != 6)
 			return;
-		int s = pserialize_read_enter();
-		struct ifnet *ifp;
+
+		s = pserialize_read_enter();
 		IFNET_READER_FOREACH(ifp) {
 			if (memcmp(macaddr, CLLADDR(ifp->if_sadl), len) == 0) {
 				device_t dv = device_find_by_xname(ifp->if_xname);
@@ -830,6 +879,8 @@ fdt_detect_root_device(device_t dev)
 			}
 		}
 		pserialize_read_exit(s);
+
+		return;
 	}
 }
 
Index: arch/evbarm/include/types.h
===================================================================
RCS file: /cvsroot/src/sys/arch/evbarm/include/types.h,v
retrieving revision 1.15
diff -p -u -r1.15 types.h
--- arch/evbarm/include/types.h	1 Apr 2021 04:35:45 -0000	1.15
+++ arch/evbarm/include/types.h	27 Jan 2023 07:22:31 -0000
@@ -3,6 +3,8 @@
 #ifndef _EVBARM_TYPES_H_
 #define	_EVBARM_TYPES_H_
 
+#define	__HAVE_CPU_BOOTCONF
+
 #ifdef __aarch64__
 #include <aarch64/types.h>