extlinux: add --device option to override device detect

Add a --device option for scripts and expert users to override the
device detection.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

2 files changed, 9 insertions, 1 deletions

diff --git a/libinstaller/syslxopt.c b/libinstaller/syslxopt.c
index e081a00e..dde4969f 100644
--- a/libinstaller/syslxopt.c
+++ b/libinstaller/syslxopt.c
@@ -66,6 +66,7 @@ const struct option long_options[] = {
     {"menu-save", 1, NULL, 'M'},
     {"mbr", 0, NULL, 'm'},	/* DOS/Win32 only */
     {"active", 0, NULL, 'a'},	/* DOS/Win32 only */
+    {"device", 1, NULL, OPT_DEVICE},
     {0, 0, 0, 0}
 };
 
@@ -87,7 +88,8 @@ void __attribute__ ((noreturn)) usage(int rv, enum syslinux_mode mode)
 	/* Mounted fs installation (extlinux) */
 	/* Actually extlinux can also use -d to provide a directory too... */
 	fprintf(stderr,
-	    "Usage: %s [options] directory\n",
+	    "Usage: %s [options] directory\n"
+	    "  --device         Force use of a specific block device (experts only)\n"
 	    program);
 	break;
 
@@ -210,6 +212,11 @@ void parse_options(int argc, char *argv[], enum syslinux_mode mode)
 	case 'a':
 	    opt.activate_partition = 1;
 	    break;
+	case OPT_DEVICE:
+	    if (mode != EXTLINUX_MODE)
+		usage(EX_USAGE, mode);
+	    opt.device = optarg;
+	    break;
 	case 'v':
 	    fprintf(stderr,
 		    "%s " VERSION_STR "  Copyright 1994-" YEAR_STR
diff --git a/libinstaller/syslxopt.h b/libinstaller/syslxopt.h
index bcbe0352..042301f6 100644
--- a/libinstaller/syslxopt.h
+++ b/libinstaller/syslxopt.h
@@ -24,6 +24,7 @@ enum long_only_opt {
     OPT_NONE,
     OPT_RESET_ADV,
     OPT_ONCE,
+    OPT_DEVICE,
 };
 
 enum syslinux_mode {