diff --git a/stand/kboot/kboot.h b/stand/kboot/kboot.h
--- a/stand/kboot/kboot.h
+++ b/stand/kboot/kboot.h
@@ -36,12 +36,14 @@
 bool hostdisk_zfs_find_default(void);
 
 /* seg.c */
+#define SYSTEM_RAM 1
 void init_avail(void);
 void need_avail(int n);
 void add_avail(uint64_t start, uint64_t end, uint64_t type);
 void remove_avail(uint64_t start, uint64_t end, uint64_t type);
 uint64_t first_avail(uint64_t align, uint64_t min_size, uint64_t type);
 void print_avail(void);
+bool populate_avail_from_iomem(void);
 
 /* util.c */
 bool file2str(const char *fn, char *buffer, size_t buflen);
diff --git a/stand/kboot/seg.c b/stand/kboot/seg.c
--- a/stand/kboot/seg.c
+++ b/stand/kboot/seg.c
@@ -195,3 +195,152 @@
 
 	return (0);
 }
+
+enum types {
+	system_ram = SYSTEM_RAM,
+	firmware_reserved,
+	linux_code,
+	linux_data,
+	linux_bss,
+	unknown,
+};
+
+static struct kv
+{
+	uint64_t	type;
+	char *		name;
+	int		flags;
+#define KV_KEEPER 1
+} str2type_kv[] = {
+	{ linux_code,		"Kernel code", KV_KEEPER },
+	{ linux_data,		"Kernel data", KV_KEEPER },
+	{ linux_bss,		"Kernel bss", KV_KEEPER },
+	{ firmware_reserved,	"reserved" },
+	{ 0, NULL },
+};
+
+static const char *
+parse_line(const char *line, uint64_t *startp, uint64_t *endp)
+{
+	const char *walker;
+	char *next;
+	uint64_t start, end;
+
+	/*
+	 * Each line is a range followed by a descriptoin of the form:
+	 * <hex-number><dash><hex-number><space><colon><space><string>
+	 * Bail if we have any parsing errors.
+	 */
+	walker = line;
+	start = strtoull(walker, &next, 16);
+	if (start == ULLONG_MAX || walker == next)
+		return (NULL);
+	walker = next;
+	if (*walker != '-')
+		return (NULL);
+	walker++;
+	end = strtoull(walker, &next, 16);
+	if (end == ULLONG_MAX || walker == next)
+		return (NULL);
+	walker = next;
+	/* Now eat the ' : ' in front of the string we want to return */
+	if (strncmp(walker, " : ", 3) != 0)
+		return (NULL);
+	*startp = start;
+	*endp = end;
+	return (walker + 3);
+}
+
+static struct kv *
+kvlookup(const char *str, struct kv *kvs, size_t nkv)
+{
+	for (int i = 0; i < nkv; i++)
+		if (strcmp(kvs[i].name, str) == 0)
+			return (&kvs[i]);
+
+	return (NULL);
+}
+
+/* Trim trailing whitespace */
+static void
+chop(char *line)
+{
+	char *ep = line + strlen(line) - 1;
+
+	while (ep >= line && isspace(*ep))
+		*ep-- = '\0';
+}
+
+#define SYSTEM_RAM_STR "System RAM"
+#define RESERVED "reserved"
+
+bool
+populate_avail_from_iomem(void)
+{
+	int fd;
+	char buf[128];
+	const char *str;
+	uint64_t start, end;
+	struct kv *kv;
+
+	fd = open("host:/proc/iomem", O_RDONLY);
+	if (fd == -1) {
+		printf("Can't get memory map\n");
+		return false;
+	}
+
+	if (fgetstr(buf, sizeof(buf), fd) < 0)
+		goto out;	/* Nothing to do ???? */
+	init_avail();
+	chop(buf);
+	while (true) {
+		/*
+		 * Look for top level items we understand.  Skip anything that's
+		 * a continuation, since we don't care here. If we care, we'll
+		 * consume them all when we recognize that top level item.
+		 */
+		if (buf[0] == ' ')	/* Continuation lines? Ignore */
+			goto next_line;
+		str = parse_line(buf, &start, &end);
+		if (str == NULL)	/* Malformed -> ignore */
+			goto next_line;
+		/*
+		 * All we care about is System RAM
+		 */
+		if (strncmp(str, SYSTEM_RAM_STR, sizeof(SYSTEM_RAM_STR) - 1) == 0)
+			add_avail(start, end, system_ram);
+		else if (strncmp(str, RESERVED, sizeof(RESERVED) - 1) == 0)
+			add_avail(start, end, firmware_reserved);
+		else
+			goto next_line;	/* Ignore hardware */
+		while (fgetstr(buf, sizeof(buf), fd) >= 0 && buf[0] == ' ') {
+			chop(buf);
+			str = parse_line(buf, &start, &end);
+			if (str == NULL)
+				break;
+			kv = kvlookup(str, str2type_kv, nitems(str2type_kv));
+			if (kv == NULL) /* failsafe for new types: igonre */
+				remove_avail(start, end, unknown);
+			else if ((kv->flags & KV_KEEPER) == 0)
+				remove_avail(start, end, kv->type);
+			/* Else no need to adjust since it's a keeper */
+		}
+
+		/*
+		 * if buf[0] == ' ' then we know that the fgetstr failed and we
+		 * should break. Otherwise fgetstr succeeded and we have a
+		 * buffer we need to examine for being a top level item.
+		 */
+		if (buf[0] == ' ')
+			break;
+		chop(buf);
+		continue; /* buf has next top level line to parse */
+next_line:
+		if (fgetstr(buf, sizeof(buf), fd) < 0)
+			break;
+	}
+
+out:
+	close(fd);
+	return true;
+}