ptgen: allow non-default placement of gpt entry table

Usually, the primary GPT entries places in the sector 2 (next sector after
the primary GPT header). The boot ROM of some SoCs (like Airoha AN7581) on
the other hand reads the bootloader code from only one fixed offset which
overlaps with the normal position of the primary GPT entries.

This patch adds a parameter to ptgen to customise the position of the primary
GPT entries.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>

1 files changed, 23 insertions, 7 deletions

diff --git a/src/ptgen.c b/src/ptgen.c
index 37eeac0..ed9efa3 100644
--- a/src/ptgen.c
+++ b/src/ptgen.c
@@ -172,6 +172,7 @@ bool use_guid_partition_table = false;
 struct partinfo parts[GPT_ENTRY_MAX];
 char *filename = NULL;
 
+uint64_t gpt_first_entry_sector = GPT_FIRST_ENTRY_SECTOR;
 
 /*
  * parse the size argument, which is either
@@ -408,15 +409,15 @@ static int gen_gptable(uint32_t signature, guid_t guid, unsigned nr)
 		.revision = cpu_to_le32(GPT_REVISION),
 		.size = cpu_to_le32(GPT_HEADER_SIZE),
 		.self = cpu_to_le64(GPT_HEADER_SECTOR),
-		.first_usable = cpu_to_le64(GPT_FIRST_ENTRY_SECTOR + GPT_ENTRY_SIZE * GPT_ENTRY_MAX / DISK_SECTOR_SIZE),
-		.first_entry = cpu_to_le64(GPT_FIRST_ENTRY_SECTOR),
+		.first_usable = cpu_to_le64(gpt_first_entry_sector + GPT_SIZE),
+		.first_entry = cpu_to_le64(gpt_first_entry_sector),
 		.disk_guid = guid,
 		.entry_num = cpu_to_le32(GPT_ENTRY_MAX),
 		.entry_size = cpu_to_le32(GPT_ENTRY_SIZE),
 	};
 	struct gpte  gpte[GPT_ENTRY_MAX];
 	uint64_t start, end;
-	uint64_t sect = GPT_SIZE + GPT_FIRST_ENTRY_SECTOR;
+	uint64_t sect = GPT_SIZE + gpt_first_entry_sector;
 	int fd, ret = -1;
 	unsigned i, pmbr = 1;
 
@@ -479,8 +480,8 @@ static int gen_gptable(uint32_t signature, guid_t guid, unsigned nr)
 	}
 
 	if ((parts[0].start != 0) &&
-	    (parts[0].actual_start > GPT_FIRST_ENTRY_SECTOR + GPT_SIZE)) {
-		gpte[GPT_ENTRY_MAX - 1].start = cpu_to_le64(GPT_FIRST_ENTRY_SECTOR + GPT_SIZE);
+	    (parts[0].actual_start > gpt_first_entry_sector + GPT_SIZE)) {
+		gpte[GPT_ENTRY_MAX - 1].start = cpu_to_le64(gpt_first_entry_sector + GPT_SIZE);
 		gpte[GPT_ENTRY_MAX - 1].end = cpu_to_le64(parts[0].actual_start - 1);
 		gpte[GPT_ENTRY_MAX - 1].type = GUID_PARTITION_BIOS_BOOT;
 		gpte[GPT_ENTRY_MAX - 1].guid = guid;
@@ -500,6 +501,10 @@ static int gen_gptable(uint32_t signature, guid_t guid, unsigned nr)
 	gpth.entry_crc32 = cpu_to_le32(gpt_crc32(gpte, GPT_ENTRY_SIZE * GPT_ENTRY_MAX));
 	gpth.crc32 = cpu_to_le32(gpt_crc32((char *)&gpth, GPT_HEADER_SIZE));
 
+	if (verbose)
+		fprintf(stderr, "PartitionEntryLBA=%" PRIu64 ", FirstUsableLBA=%" PRIu64 ", LastUsableLBA=%" PRIu64 "\n",
+			gpt_first_entry_sector, gpt_first_entry_sector + GPT_SIZE, end - GPT_SIZE - 1);
+
 	if ((fd = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0644)) < 0) {
 		fprintf(stderr, "Can't open output file '%s'\n",filename);
 		return ret;
@@ -528,7 +533,7 @@ static int gen_gptable(uint32_t signature, guid_t guid, unsigned nr)
 		goto fail;
 	}
 
-	lseek(fd, GPT_FIRST_ENTRY_SECTOR * DISK_SECTOR_SIZE, SEEK_SET);
+	lseek(fd, gpt_first_entry_sector * DISK_SECTOR_SIZE, SEEK_SET);
 	if (write(fd, &gpte, GPT_ENTRY_SIZE * GPT_ENTRY_MAX) != GPT_ENTRY_SIZE * GPT_ENTRY_MAX) {
 		fputs("write failed.\n", stderr);
 		goto fail;
@@ -569,7 +574,9 @@ static void usage(char *prog)
 {
 	fprintf(stderr, "Usage: %s [-v] [-n] [-g] -h <heads> -s <sectors> -o <outputfile>\n"
 			"          [-a <part number>] [-l <align kB>] [-G <guid>]\n"
+			"          [-e <gpt_entry_offset>]\n"
 			"          [[-t <type> | -T <GPT part type>] [-r] [-N <name>] -p <size>[@<start>]...] \n", prog);
+
 	exit(EXIT_FAILURE);
 }
 
@@ -606,7 +613,7 @@ int main (int argc, char **argv)
 	guid_t guid = GUID_INIT( signature, 0x2211, 0x4433, \
 			0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0x00);
 
-	while ((ch = getopt(argc, argv, "h:s:p:a:t:T:o:vnHN:gl:rS:G:")) != -1) {
+	while ((ch = getopt(argc, argv, "h:s:p:a:t:T:o:vnHN:gl:rS:G:e:")) != -1) {
 		switch (ch) {
 		case 'o':
 			filename = optarg;
@@ -623,6 +630,15 @@ int main (int argc, char **argv)
 		case 'H':
 			hybrid = 1;
 			break;
+		case 'e':
+			/* based on DISK_SECTOR_SIZE = 512 */
+			gpt_first_entry_sector = 2 * to_kbytes(optarg);
+			if (gpt_first_entry_sector < GPT_FIRST_ENTRY_SECTOR) {
+				fprintf(stderr, "GPT First Entry offset must not be smaller than %d KBytes\n",
+					GPT_FIRST_ENTRY_SECTOR / 2);
+				exit(EXIT_FAILURE);
+			}
+			break;
 		case 'h':
 			heads = (int)strtoul(optarg, NULL, 0);
 			break;