--- fwmaker/src/cmds.c	2026/01/04 18:08:18	1.1
+++ fwmaker/src/cmds.c	2026/01/04 18:52:50	1.2
@@ -10,7 +10,8 @@ cmd_Show(void *lb, int idx, char **args)
 
 	printf("FW Image file: %s\n", image);
 	printf("FW Image size: %zu\n", imgsiz);
-	printf("FW Image descriptor: %d\n\n", imgfd);
+	printf("FW Image descriptor: %d\n", imgfd);
+	printf("FW Image empty byte: 0x%02x\n\n", fillCh);
 
 	printf("MTD loaded: 0x%zx\n", mtd.mtd_fsiz);
 	printf("MTD file: %s\n", mtd.mtd_file);
@@ -228,6 +229,10 @@ cmd_Mtd(void *lb, int idx, char **args)
 int
 cmd_Image(void *lb, int idx, char **args)
 {
+	u_char buf[BUFSIZ];
+	int wlen;
+	size_t siz;
+
 	ETRACE();
 
 	args++;
@@ -269,19 +274,52 @@ cmd_Image(void *lb, int idx, char **args)
 			return -1;
 		}
 		if (imageOpen(O_CREAT) > 2) {
-			imgsiz = (size_t) strtol(args[1], NULL, 0);
+			memset(buf, fillCh, sizeof buf);
+			imgsiz = siz = (size_t) strtol(args[1], NULL, 0);
 			if (ftruncate(imgfd, imgsiz) == -1) {
 				ESYSERR(0);
 				imageClose();
 				unlink(image);
 				return -1;
-			} else
-				EVERBOSE(1, "Image '%s' created with size=%lu\n", image, imgsiz);
+			}
+			lseek(imgfd, 0, SEEK_SET);
+			while (siz > 0) {
+				wlen = MIN(siz, sizeof buf);
+				wlen = write(imgfd, buf, wlen);
+				if (wlen < 1) {
+					ESYSERR(0);
+					imageClose();
+					unlink(image);
+					return -1;
+				} else
+					siz -= wlen;
+			}
+			EVERBOSE(1, "Image '%s' created successful with size=%lu/remain=#%lu bytes\n",
+					image, imgsiz, siz);
 		}
 	} else {
 		printf("Error:: unknown command '%s'\n", args[0]);
 		return -1;
 	}
+
+	return 0;
+}
+
+int
+cmd_FillCh(void *lb, int idx, char **args)
+{
+	char str[STRSIZ];
+
+	ETRACE();
+
+	args++;
+	if (!args[0]) {
+		if (!dialog(lb, "Byte=", str, sizeof str))
+			fillCh = (u_char) strtol(str, NULL, 0);
+		else
+			return -1;
+	} else
+		fillCh = (u_char) strtol(args[0], NULL, 0);
 
 	return 0;
 }