firmware-utils: tplink-safeloader: refactor meta-partition padding

Because some padding values in the TP-Link safeloader image generation
were hardcoded, different values were sometimes used throughout a
factory image. TP-Link's upgrade images use the same value everywhere,
so let's do the same here.

Although a lot of TP-Link's safeloader images have padded partition
payloads, images for the EAP-series of AC devices don't. This padding is
therefore also made optional.

By replacing the type of the padding value byte with a wider datatype,
new values outside of the previously valid range become available. Use
these new values to denote that padding should not be performed.
Because char might be signed, also replace the char literals by a
numeric literal. Otherwise '\xff' might be sign extended to 0xffff.

This results in factory images differing by 1 byte for:
* C2600
* ARCHER-C5-V2
* ARCHERC9
* TLWA850REV2
* TLWA855REV1
* TL-WPA8630P-V2-EU
* TL-WPA8630P-V2-INT
* TL-WPA8630P-V2.1-EU
* TLWR1043NDV4
* TL-WR902AC-V1
* TLWR942NV1
* RE200-V2
* RE200-V3
* RE220-V2
* RE305-V1
* RE350-V1
* RE350K-V1
* RE355
* RE450
* RE450-V2
* RE450-V3
* RE500-V1
* RE650-V1

The following factory images no longer have padding, shrinking the
factory images by a few bytes for:
* EAP225-OUTDOOR-V1
* EAP225-V3
* EAP225-WALL-V2
* EAP245-V1
* EAP245-V3

Signed-off-by: Sander Vanheule <sander@svanheule.net>

1 files changed, 88 insertions, 67 deletions

diff --git a/tools/firmware-utils/src/tplink-safeloader.c b/tools/firmware-utils/src/tplink-safeloader.c
index 41b3b8aff9..ce07a95574 100644
--- a/tools/firmware-utils/src/tplink-safeloader.c
+++ b/tools/firmware-utils/src/tplink-safeloader.c
@@ -70,12 +70,22 @@ struct flash_partition_entry {
 	uint32_t size;
 };
 
+/** Partition trailing padding definitions
+ * Values 0x00 to 0xff are reserved to indicate the padding value
+ * Values from 0x100 are reserved to indicate other behaviour */
+enum partition_trail_value {
+	PART_TRAIL_00   = 0x00,
+	PART_TRAIL_FF   = 0xff,
+	PART_TRAIL_MAX  = 0xff,
+	PART_TRAIL_NONE = 0x100
+};
+
 /** Firmware layout description */
 struct device_info {
 	const char *id;
 	const char *vendor;
 	const char *support_list;
-	char support_trail;
+	enum partition_trail_value part_trail;
 	const char *soft_ver;
 	uint32_t soft_ver_compat_level;
 	struct flash_partition_entry partitions[MAX_PARTITIONS+1];
@@ -135,7 +145,7 @@ static struct device_info boards[] = {
 			"CPE220(TP-LINK|UN|N300-2):1.1\r\n"
 			"CPE220(TP-LINK|US|N300-2):1.1\r\n"
 			"CPE220(TP-LINK|EU|N300-2):1.1\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -175,7 +185,7 @@ static struct device_info boards[] = {
 			"CPE210(TP-LINK|UN|N300-2):2.0\r\n"
 			"CPE210(TP-LINK|EU|N300-2):2.0\r\n"
 			"CPE210(TP-LINK|US|N300-2):2.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -217,7 +227,7 @@ static struct device_info boards[] = {
 			"CPE210(TP-LINK|EU|N300-2|45550000):3.20\r\n"
 			"CPE210(TP-LINK|UN|N300-2|00000000):3.20\r\n"
 			"CPE210(TP-LINK|US|N300-2|55530000):3.20\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -258,7 +268,7 @@ static struct device_info boards[] = {
 			"CPE220(TP-LINK|UN|N300-2):2.0\r\n"
 			"CPE220(TP-LINK|EU|N300-2):2.0\r\n"
 			"CPE220(TP-LINK|US|N300-2):2.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -298,7 +308,7 @@ static struct device_info boards[] = {
 			"CPE220(TP-LINK|UN|N300-2):3.0\r\n"
 			"CPE220(TP-LINK|EU|N300-2):3.0\r\n"
 			"CPE220(TP-LINK|US|N300-2):3.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -337,7 +347,7 @@ static struct device_info boards[] = {
 			"CPE520(TP-LINK|UN|N300-5):1.1\r\n"
 			"CPE520(TP-LINK|US|N300-5):1.1\r\n"
 			"CPE520(TP-LINK|EU|N300-5):1.1\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -379,7 +389,7 @@ static struct device_info boards[] = {
 			"CPE510(TP-LINK|UN|N300-5):2.0\r\n"
 			"CPE510(TP-LINK|EU|N300-5):2.0\r\n"
 			"CPE510(TP-LINK|US|N300-5):2.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -421,7 +431,7 @@ static struct device_info boards[] = {
 			"CPE510(TP-LINK|UN|N300-5):3.0\r\n"
 			"CPE510(TP-LINK|EU|N300-5):3.0\r\n"
 			"CPE510(TP-LINK|US|N300-5):3.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -461,7 +471,7 @@ static struct device_info boards[] = {
 			"CPE610(TP-LINK|UN|N300-5):1.0\r\n"
 			"CPE610(TP-LINK|EU|N300-5):1.0\r\n"
 			"CPE610(TP-LINK|US|N300-5):1.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -501,7 +511,7 @@ static struct device_info boards[] = {
 			"CPE610(TP-LINK|UN|N300-5):2.0\r\n"
 			"CPE610(TP-LINK|EU|N300-5):2.0\r\n"
 			"CPE610(TP-LINK|US|N300-5):2.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -533,7 +543,7 @@ static struct device_info boards[] = {
 			"WBS210(TP-LINK|UN|N300-2):1.20\r\n"
 			"WBS210(TP-LINK|US|N300-2):1.20\r\n"
 			"WBS210(TP-LINK|EU|N300-2):1.20\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -565,7 +575,7 @@ static struct device_info boards[] = {
 			"WBS210(TP-LINK|UN|N300-2|00000000):2.0\r\n"
 			"WBS210(TP-LINK|US|N300-2|55530000):2.0\r\n"
 			"WBS210(TP-LINK|EU|N300-2|45550000):2.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -598,7 +608,7 @@ static struct device_info boards[] = {
 			"WBS510(TP-LINK|US|N300-5):1.20\r\n"
 			"WBS510(TP-LINK|EU|N300-5):1.20\r\n"
 			"WBS510(TP-LINK|CA|N300-5):1.20\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -631,7 +641,7 @@ static struct device_info boards[] = {
 			"WBS510(TP-LINK|US|N300-5|55530000):2.0\r\n"
 			"WBS510(TP-LINK|EU|N300-5|45550000):2.0\r\n"
 			"WBS510(TP-LINK|CA|N300-5|43410000):2.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -662,7 +672,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\r\n"
 			"{product_name:Archer C2600,product_ver:1.0.0,special_id:00000000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/**
@@ -713,7 +723,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer A7,product_ver:5.0.0,special_id:43410000}\n"
 			"{product_name:Archer A7,product_ver:5.0.0,special_id:4A500000}\n"
 			"{product_name:Archer A7,product_ver:5.0.0,special_id:54570000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.0.0\n",
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -751,7 +761,7 @@ static struct device_info boards[] = {
 			"{product_name:ArcherC2,product_ver:3.0.0,special_id:00000000}\n"
 			"{product_name:ArcherC2,product_ver:3.0.0,special_id:55530000}\n"
 			"{product_name:ArcherC2,product_ver:3.0.0,special_id:45550000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:3.0.1\n",
 
 		/** We're using a dynamic kernel/rootfs split here */
@@ -789,7 +799,7 @@ static struct device_info boards[] = {
 			"{product_name:ArcherC25,product_ver:1.0.0,special_id:00000000}\n"
 			"{product_name:ArcherC25,product_ver:1.0.0,special_id:55530000}\n"
 			"{product_name:ArcherC25,product_ver:1.0.0,special_id:45550000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.0.0\n",
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -828,7 +838,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C58,product_ver:1.0.0,special_id:00000000}\r\n"
 			"{product_name:Archer C58,product_ver:1.0.0,special_id:45550000}\r\n"
 			"{product_name:Archer C58,product_ver:1.0.0,special_id:55530000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.0.0\n",
 
 		.partitions = {
@@ -863,7 +873,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C59,product_ver:1.0.0,special_id:45550000}\r\n"
 			"{product_name:Archer C59,product_ver:1.0.0,special_id:52550000}\r\n"
 			"{product_name:Archer C59,product_ver:1.0.0,special_id:55530000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.0.0\n",
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -901,7 +911,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C59,product_ver:2.0.0,special_id:00000000}\r\n"
 			"{product_name:Archer C59,product_ver:2.0.0,special_id:45550000}\r\n"
 			"{product_name:Archer C59,product_ver:2.0.0,special_id:55530000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:2.0.0 Build 20161206 rel.7303\n",
 
 		/** We're using a dynamic kernel/rootfs split here */
@@ -941,7 +951,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C6,product_ver:2.0.0,special_id:45550000}\r\n"
 			"{product_name:Archer C6,product_ver:2.0.0,special_id:52550000}\r\n"
 			"{product_name:Archer C6,product_ver:2.0.0,special_id:4A500000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.9.1\n",
 
 		.partitions = {
@@ -976,7 +986,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer A6,product_ver:2.0.0,special_id:55530000}\n"
 			"{product_name:Archer A6,product_ver:2.0.0,special_id:54570000}\n"
 			"{product_name:Archer C6,product_ver:2.0.0,special_id:55530000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.9.1\n",
 
 		.partitions = {
@@ -1011,7 +1021,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C60,product_ver:1.0.0,special_id:00000000}\r\n"
 			"{product_name:Archer C60,product_ver:1.0.0,special_id:45550000}\r\n"
 			"{product_name:Archer C60,product_ver:1.0.0,special_id:55530000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.0.0\n",
 
 		.partitions = {
@@ -1045,7 +1055,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C60,product_ver:2.0.0,special_id:42520000}\r\n"
 			"{product_name:Archer C60,product_ver:2.0.0,special_id:45550000}\r\n"
 			"{product_name:Archer C60,product_ver:2.0.0,special_id:55530000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:2.0.0\n",
 
 		.partitions = {
@@ -1081,7 +1091,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C60,product_ver:3.0.0,special_id:42520000}\r\n"
 			"{product_name:Archer C60,product_ver:3.0.0,special_id:45550000}\r\n"
 			"{product_name:Archer C60,product_ver:3.0.0,special_id:55530000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:3.0.0\n",
 
 		.partitions = {
@@ -1117,7 +1127,7 @@ static struct device_info boards[] = {
 			"{product_name:ArcherC5,product_ver:2.0.0,special_id:00000000}\r\n"
 			"{product_name:ArcherC5,product_ver:2.0.0,special_id:55530000}\r\n"
 			"{product_name:ArcherC5,product_ver:2.0.0,special_id:4A500000}\r\n", /* JP version */
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1158,7 +1168,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C7,product_ver:4.0.0,special_id:54570000}\n"
 			"{product_name:Archer C7,product_ver:4.0.0,special_id:55530000}\n"
 			"{product_name:Archer C7,product_ver:4.0.0,special_id:43410000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.0.0\n",
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -1203,7 +1213,7 @@ static struct device_info boards[] = {
 			"{product_name:Archer C7,product_ver:5.0.0,special_id:52550000}\n"
 			"{product_name:Archer C7,product_ver:5.0.0,special_id:4B520000}\n",
 
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.0.0\n",
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -1246,7 +1256,7 @@ static struct device_info boards[] = {
 			"{product_name:ArcherC9,"
 			"product_ver:1.0.0,"
 			"special_id:00000000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1279,7 +1289,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\r\n"
 			"EAP120(TP-LINK|UN|N300-2):1.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = 0xff,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1308,7 +1318,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\r\n"
 			"EAP225-Outdoor(TP-Link|UN|AC1200-D):1.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = PART_TRAIL_NONE,
 		.soft_ver = NULL,
 		.soft_ver_compat_level = 1,
 
@@ -1337,7 +1347,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\r\n"
 			"EAP225(TP-Link|UN|AC1350-D):3.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = PART_TRAIL_NONE,
 		.soft_ver = NULL,
 		.soft_ver_compat_level = 1,
 
@@ -1366,7 +1376,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\r\n"
 			"EAP225-Wall(TP-Link|UN|AC1200-D):2.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = PART_TRAIL_NONE,
 		.soft_ver = NULL,
 		.soft_ver_compat_level = 1,
 
@@ -1395,7 +1405,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\r\n"
 			"EAP245(TP-LINK|UN|AC1750-D):1.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = PART_TRAIL_NONE,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1421,7 +1431,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\r\n"
 			"EAP245(TP-Link|UN|AC1750-D):3.0\r\n",
-		.support_trail = '\xff',
+		.part_trail = PART_TRAIL_NONE,
 		.soft_ver = NULL,
 		.soft_ver_compat_level = 1,
 
@@ -1463,7 +1473,7 @@ static struct device_info boards[] = {
 			"{product_name:TL-WA850RE,product_ver:2.0.0,special_id:43410000}\n"
 			"{product_name:TL-WA850RE,product_ver:2.0.0,special_id:41550000}\n"
 			"{product_name:TL-WA850RE,product_ver:2.0.0,special_id:52550000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/**
@@ -1505,7 +1515,7 @@ static struct device_info boards[] = {
 			"{product_name:TL-WA855RE,product_ver:1.0.0,special_id:43410000}\n"
 			"{product_name:TL-WA855RE,product_ver:1.0.0,special_id:41550000}\n"
 			"{product_name:TL-WA855RE,product_ver:1.0.0,special_id:52550000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1536,7 +1546,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\n"
 			"{product_name:TL-WPA8630P,product_ver:2.0.0,special_id:45550000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1573,7 +1583,7 @@ static struct device_info boards[] = {
 			"{product_name:TL-WPA8630P,product_ver:2.0.0,special_id:41550000}\n"
 			"{product_name:TL-WPA8630P,product_ver:2.0.0,special_id:44450000}\n"
 			"{product_name:TL-WPA8630P,product_ver:2.1.0,special_id:41550000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1608,7 +1618,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\n"
 			"{product_name:TL-WPA8630P,product_ver:2.1.0,special_id:45550000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1644,7 +1654,7 @@ static struct device_info boards[] = {
 			"SupportList:\n"
 			"{product_name:TL-WR1043N,product_ver:5.0.0,special_id:45550000}\n"
 			"{product_name:TL-WR1043N,product_ver:5.0.0,special_id:55530000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.0.0\n",
 		.partitions = {
 			{"factory-boot", 0x00000, 0x20000},
@@ -1678,7 +1688,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\n"
 			"{product_name:TL-WR1043ND,product_ver:4.0.0,special_id:45550000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -1711,7 +1721,7 @@ static struct device_info boards[] = {
 			"SupportList:\n"
 			"{product_name:TL-WR902AC,product_ver:1.0.0,special_id:45550000}\n"
 			"{product_name:TL-WR902AC,product_ver:1.0.0,special_id:55530000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/**
@@ -1747,7 +1757,7 @@ static struct device_info boards[] = {
 			"SupportList:\r\n"
 			"{product_name:TL-WR942N,product_ver:1.0.0,special_id:00000000}\r\n"
 			"{product_name:TL-WR942N,product_ver:1.0.0,special_id:52550000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1794,7 +1804,7 @@ static struct device_info boards[] = {
 			"{product_name:RE200,product_ver:2.0.0,special_id:52550000}\n"
 			"{product_name:RE200,product_ver:2.0.0,special_id:54570000}\n"
 			"{product_name:RE200,product_ver:2.0.0,special_id:55530000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1838,7 +1848,7 @@ static struct device_info boards[] = {
 			"{product_name:RE200,product_ver:3.0.0,special_id:52550000}\n"
 			"{product_name:RE200,product_ver:3.0.0,special_id:54570000}\n"
 			"{product_name:RE200,product_ver:3.0.0,special_id:55530000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1882,7 +1892,7 @@ static struct device_info boards[] = {
 			"{product_name:RE200,product_ver:4.0.0,special_id:45530000}\n"
 			"{product_name:RE200,product_ver:4.0.0,special_id:49440000}\n"
 			"{product_name:RE200,product_ver:4.0.0,special_id:45470000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = "soft_ver:1.1.0\n",
 
 		.partitions = {
@@ -1925,7 +1935,7 @@ static struct device_info boards[] = {
 			"{product_name:RE220,product_ver:2.0.0,special_id:52550000}\n"
 			"{product_name:RE220,product_ver:2.0.0,special_id:54570000}\n"
 			"{product_name:RE220,product_ver:2.0.0,special_id:55530000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1962,7 +1972,7 @@ static struct device_info boards[] = {
 			"{product_name:RE305,product_ver:1.0.0,special_id:4b520000}\n"
 			"{product_name:RE305,product_ver:1.0.0,special_id:41550000}\n"
 			"{product_name:RE305,product_ver:1.0.0,special_id:43410000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		.partitions = {
@@ -1998,7 +2008,7 @@ static struct device_info boards[] = {
 			"{product_name:RE350,product_ver:1.0.0,special_id:43410000}\n"
 			"{product_name:RE350,product_ver:1.0.0,special_id:4b520000}\n"
 			"{product_name:RE350,product_ver:1.0.0,special_id:4a500000}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/** We're using a dynamic kernel/rootfs split here */
@@ -2029,7 +2039,7 @@ static struct device_info boards[] = {
 		.support_list =
 			"SupportList:\n"
 			"{product_name:RE350K,product_ver:1.0.0,special_id:00000000,product_region:US}\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/** We're using a dynamic kernel/rootfs split here */
@@ -2068,7 +2078,7 @@ static struct device_info boards[] = {
 			"{product_name:RE355,product_ver:1.0.0,special_id:41550000}\r\n"
 			"{product_name:RE355,product_ver:1.0.0,special_id:4B520000}\r\n"
 			"{product_name:RE355,product_ver:1.0.0,special_id:55534100}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -2106,7 +2116,7 @@ static struct device_info boards[] = {
 			"{product_name:RE450,product_ver:1.0.0,special_id:41550000}\r\n"
 			"{product_name:RE450,product_ver:1.0.0,special_id:4B520000}\r\n"
 			"{product_name:RE450,product_ver:1.0.0,special_id:55534100}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/** We're using a dynamic kernel/rootfs split here */
@@ -2145,7 +2155,7 @@ static struct device_info boards[] = {
 			"{product_name:RE450,product_ver:2.0.0,special_id:41530000}\r\n"
 			"{product_name:RE450,product_ver:2.0.0,special_id:4B520000}\r\n"
 			"{product_name:RE450,product_ver:2.0.0,special_id:42520000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -2184,7 +2194,7 @@ static struct device_info boards[] = {
 			"{product_name:RE450,product_ver:3.0.0,special_id:41530000}\r\n"
 			"{product_name:RE450,product_ver:3.0.0,special_id:4B520000}\r\n"
 			"{product_name:RE450,product_ver:3.0.0,special_id:42520000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -2222,7 +2232,7 @@ static struct device_info boards[] = {
 			"{product_name:RE500,product_ver:1.0.0,special_id:43410000}\r\n"
 			"{product_name:RE500,product_ver:1.0.0,special_id:41550000}\r\n"
 			"{product_name:RE500,product_ver:1.0.0,special_id:41530000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -2259,7 +2269,7 @@ static struct device_info boards[] = {
 			"{product_name:RE650,product_ver:1.0.0,special_id:43410000}\r\n"
 			"{product_name:RE650,product_ver:1.0.0,special_id:41550000}\r\n"
 			"{product_name:RE650,product_ver:1.0.0,special_id:41530000}\r\n",
-		.support_trail = '\x00',
+		.part_trail = 0x00,
 		.soft_ver = NULL,
 
 		/* We're using a dynamic kernel/rootfs split here */
@@ -2303,15 +2313,23 @@ static inline void put32(uint8_t *buf, uint32_t val) {
 	buf[3] = val;
 }
 
+static inline bool meta_partition_should_pad(enum partition_trail_value pv)
+{
+	return (pv >= 0) && (pv <= PART_TRAIL_MAX);
+}
+
 /** Allocate a padded meta partition with a correctly initialised header
  * If the `data` pointer is NULL, then the required space is only allocated,
  * otherwise `data_len` bytes will be copied from `data` into the partition
  * entry. */
 static struct image_partition_entry init_meta_partition_entry(
 	const char *name, const void *data, uint32_t data_len,
-	uint8_t pad_value)
+	enum partition_trail_value pad_value)
 {
-	uint32_t total_len = sizeof(struct meta_header) + data_len + 1;
+	uint32_t total_len = sizeof(struct meta_header) + data_len;
+	if (meta_partition_should_pad(pad_value))
+		total_len += 1;
+
 	struct image_partition_entry entry = {
 		.name = name,
 		.size = total_len,
@@ -2327,7 +2345,8 @@ static struct image_partition_entry init_meta_partition_entry(
 	if (data)
 		memcpy(entry.data+sizeof(*header), data, data_len);
 
-	entry.data[total_len - 1] = pad_value;
+	if (meta_partition_should_pad(pad_value))
+		entry.data[total_len - 1] = (uint8_t) pad_value;
 
 	return entry;
 }
@@ -2405,7 +2424,7 @@ static struct image_partition_entry make_soft_version(
 	if (info->soft_ver) {
 		uint32_t len = strlen(info->soft_ver) + 1;
 		return init_meta_partition_entry("soft-version",
-			info->soft_ver, len, 0);
+			info->soft_ver, len, info->part_trail);
 	}
 
 	time_t t;
@@ -2434,10 +2453,11 @@ static struct image_partition_entry make_soft_version(
 
 	if (info->soft_ver_compat_level == 0)
 		return init_meta_partition_entry("soft-version", &s,
-			(uint8_t *)(&s.compat_level) - (uint8_t *)(&s), 0xff);
+			(uint8_t *)(&s.compat_level) - (uint8_t *)(&s),
+			info->part_trail);
 	else
 		return init_meta_partition_entry("soft-version", &s,
-			sizeof(s), 0xff);
+			sizeof(s), info->part_trail);
 }
 
 /** Generates the support-list partition */
@@ -2446,14 +2466,15 @@ static struct image_partition_entry make_support_list(
 {
 	uint32_t len = strlen(info->support_list);
 	return init_meta_partition_entry("support-list", info->support_list,
-		len, info->support_trail);
+		len, info->part_trail);
 }
 
 /** Partition with extra-para data */
 static struct image_partition_entry make_extra_para(
 	const struct device_info *info, const uint8_t *extra_para, size_t len)
 {
-	return init_meta_partition_entry("extra-para", extra_para, len, 0x00);
+	return init_meta_partition_entry("extra-para", extra_para, len,
+		info->part_trail);
 }
 
 /** Creates a new image partition with an arbitrary name from a file */