[Command] Add "sanboot" command.

src/config.h

 #define	ROUTE_CMD		/* Routing table management commands */
 #define IMAGE_CMD		/* Image management commands */
 #define DHCP_CMD		/* DHCP management commands */
+#define SANBOOT_CMD		/* SAN boot commands */
 
 /* @END general.h */ 
 

src/core/config.c

 #ifdef DHCP_CMD
 REQUIRE_OBJECT ( dhcp_cmd );
 #endif
+#ifdef SANBOOT_CMD
+REQUIRE_OBJECT ( sanboot_cmd );
+#endif
 
 /*
  * Drag in miscellaneous objects

src/hci/commands/sanboot_cmd.c

+#include <stdio.h>
+#include <string.h>
+#include <getopt.h>
+#include <gpxe/command.h>
+#include <usr/autoboot.h>
+
+/**
+ * "sanboot" command syntax message
+ *
+ * @v argv		Argument list
+ */
+static void sanboot_syntax ( char **argv ) {
+	printf ( "Usage:\n"
+		 "  %s <root-path>\n"
+		 "\n"
+		 "Boot from SAN target\n",
+		 argv[0] );
+}
+
+/**
+ * The "sanboot" command
+ *
+ * @v argc		Argument count
+ * @v argv		Argument list
+ * @ret rc		Exit code
+ */
+static int sanboot_exec ( int argc, char **argv ) {
+	static struct option longopts[] = {
+		{ "help", 0, NULL, 'h' },
+		{ NULL, 0, NULL, 0 },
+	};
+	const char *root_path = NULL;
+	int c;
+	int rc;
+
+	/* Parse options */
+	while ( ( c = getopt_long ( argc, argv, "h", longopts, NULL ) ) >= 0 ){
+		switch ( c ) {
+		case 'h':
+			/* Display help text */
+		default:
+			/* Unrecognised/invalid option */
+			sanboot_syntax ( argv );
+			return 1;
+		}
+	}
+
+	/* Need exactly one image name remaining after the options */
+	if ( optind != ( argc - 1 ) ) {
+		sanboot_syntax ( argv );
+		return 1;
+	}
+	root_path = argv[optind];
+
+	/* Boot from root path */
+	if ( ( rc = boot_root_path ( root_path ) ) != 0 ) {
+		printf ( "Could not boot from %s: %s\n",
+			 root_path, strerror ( rc ) );
+		return 1;
+	}
+
+	return 0;
+}
+
+struct command sanboot_command __command = {
+	.name = "sanboot",
+	.exec = sanboot_exec,
+};

src/include/usr/autoboot.h

  */
 
 extern void autoboot ( void );
+extern int boot_root_path ( const char *root_path );
 
 #endif /* _USR_AUTOBOOT_H */

src/usr/autoboot.c

  * @v root_path		Root path
  * @ret rc		Return status code
  */
-static int boot_root_path ( const char *root_path ) {
+int boot_root_path ( const char *root_path ) {
 
 	/* Quick hack */
 	if ( strncmp ( root_path, "iscsi:", 6 ) == 0 ) {