From: Alison Chaiken alison@peloton-tech.com
This patch provides support in u-boot for renaming GPT partitions. The renaming is accomplished via a new 'gpt flip' command.
The concept for the bootloader state machine is the following:
-- u-boot renames ‘primary’ partitions as ‘candidate’ and tries to boot them. -- Linux, at boot, will rename ‘candidate’ partitions as ‘primary’. -- If u-boot sees a ‘candidate’ partition after a boot attempt, it tries to boot the ‘backup’ partition.
Rewriting the partition table has the side-effect that all partitions end up with "msftdata" flag set. The reason is that partition type PARTITION_BASIC_DATA_GUID is hard-coded in the gpt_fill_pte() function. This does not appear to cause any harm.
Signed-off-by: Alison Chaiken alison@peloton-tech.com --- cmd/Kconfig | 7 ++ cmd/gpt.c | 199 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- doc/README.gpt | 13 ++++ 3 files changed, 215 insertions(+), 4 deletions(-)
diff --git a/cmd/Kconfig b/cmd/Kconfig index 6f75b86..8b925e5 100644 --- a/cmd/Kconfig +++ b/cmd/Kconfig @@ -593,6 +593,13 @@ config CMD_GPT Enable the 'gpt' command to ready and write GPT style partition tables.
+config CMD_GPT_FLIP + bool "GPT flip-partitions command" + depends on CMD_GPT + help + Enables the 'gpt' command to write modified GPT partition + tables via the 'gpt flip' command. + config CMD_ARMFLASH #depends on FLASH_CFI_DRIVER bool "armflash" diff --git a/cmd/gpt.c b/cmd/gpt.c index 5c2651f..f6968de 100644 --- a/cmd/gpt.c +++ b/cmd/gpt.c @@ -20,6 +20,7 @@ #include <div64.h> #include <memalign.h> #include <linux/compat.h> +#include <linux/sizes.h>
static LIST_HEAD(disk_partitions);
@@ -190,16 +191,33 @@ static struct disk_part *allocate_disk_part(disk_partition_t *info, int partnum) return newpart; }
+static void prettyprint_part_size(char *sizestr, unsigned long partsize, + unsigned long blksize) +{ + unsigned long long partbytes; + unsigned long partmegabytes; + + partbytes = partsize * blksize; + partmegabytes = lldiv(partbytes, SZ_1M); + snprintf(sizestr, 16, "%luMiB", partmegabytes); +} + static void print_gpt_info(void) { struct list_head *pos; struct disk_part *curr; + char partstartstr[16]; + char partsizestr[16];
list_for_each(pos, &disk_partitions) { curr = list_entry(pos, struct disk_part, list); + prettyprint_part_size(partstartstr, (unsigned long)curr->gpt_part_info.start, + (unsigned long) curr->gpt_part_info.blksz); + prettyprint_part_size(partsizestr, (unsigned long)curr->gpt_part_info.size, + (unsigned long) curr->gpt_part_info.blksz); + printf("Partition %d:\n", curr->partnum); - printf("1st block %x, size %x\n", (unsigned)curr->gpt_part_info.start, - (unsigned)curr->gpt_part_info.size); + printf("Start %s, size %s\n", partstartstr, partsizestr); printf("Block size %lu, name %s\n", curr->gpt_part_info.blksz, curr->gpt_part_info.name); printf("Type %s, bootable %d\n", curr->gpt_part_info.type, @@ -211,6 +229,85 @@ static void print_gpt_info(void) } }
+#ifdef CONFIG_CMD_GPT_FLIP +static int calc_parts_list_len(int numparts) +{ + /* + * prefatory string: + * doc/README.GPT, suggests that + * int partlistlen = UUID_STR_LEN + 1 + strlen("partitions=uuid_disk="); + * is correct, but extract_val() expects "uuid_disk" first. + */ + int partlistlen = UUID_STR_LEN + 1 + strlen("uuid_disk="); + /* for the comma */ + partlistlen++; + + /* per-partition additions; numparts starts at 1, so this should be correct */ + partlistlen += numparts * (strlen("name=,") + PART_NAME_LEN + 1); + /* 17 because partstr in create_gpt_partitions_list() is 16 chars */ + partlistlen += numparts * (strlen("start=MiB,") + 17); + partlistlen += numparts * (strlen("size=MiB,") + 17); + partlistlen += numparts * (strlen("uuid=;") + UUID_STR_LEN + 1); + /* for the terminating null */ + partlistlen++; + debug("Length of partitions_list is %d for %d partitions\n", partlistlen, + numparts); + return partlistlen; +} + +/* + * create the string that upstream 'gpt write' command will accept as an + * argument + * + * From doc/README.gpt, Format of partitions layout: + * "partitions=uuid_disk=...;name=u-boot,size=60MiB,uuid=...; + * name=kernel,size=60MiB,uuid=...;" + * The fields 'name' and 'size' are mandatory for every partition. + * The field 'start' is optional. The fields 'uuid' and 'uuid_disk' + * are optional if CONFIG_RANDOM_UUID is enabled. + */ +static int create_gpt_partitions_list(int numparts, const char *guid, char *partitions_list) +{ + struct list_head *pos; + struct disk_part *curr; + char partstr[PART_NAME_LEN + 1]; + + if (!partitions_list) + return -1; + + /* + * README.gpt specifies starting with "partitions=" like so: + * strcpy(partitions_list, "partitions=uuid_disk="); + * but that breaks extract_val, which doesn't skip over 'partitions='. + */ + strcpy(partitions_list, "uuid_disk="); + strncat(partitions_list, guid, UUID_STR_LEN + 1); + strcat(partitions_list, ";"); + + list_for_each(pos, &disk_partitions) { + curr = list_entry(pos, struct disk_part, list); + strcat(partitions_list, "name="); + strncat(partitions_list, (const char *)curr->gpt_part_info.name, PART_NAME_LEN + 1); + strcat(partitions_list, ",start="); + prettyprint_part_size(partstr, (unsigned long)curr->gpt_part_info.start, + (unsigned long) curr->gpt_part_info.blksz); + /* one extra byte for NULL */ + strncat(partitions_list, partstr, PART_NAME_LEN + 1); + strcat(partitions_list, ",size="); + /* lbaint_t is unsigned long, per include/ide.h */ + prettyprint_part_size(partstr, (unsigned long)curr->gpt_part_info.size, + (unsigned long) curr->gpt_part_info.blksz); + strncat(partitions_list, partstr, PART_NAME_LEN + 1); + + strcat(partitions_list, ",uuid="); + strncat(partitions_list, (const char *)curr->gpt_part_info.uuid, + UUID_STR_LEN + 1); + strcat(partitions_list, ";"); + } + return 0; +} +#endif + /* * read partition info into disk_partitions list where * it can be printed or modified @@ -222,8 +319,11 @@ static int get_gpt_info(struct blk_desc *dev_desc) disk_partition_t info; struct disk_part *new_disk_part;
- if (disk_partitions.next == NULL) - INIT_LIST_HEAD(&disk_partitions); + /* + * Always re-read partition info from device, in case + * it has changed + */ + INIT_LIST_HEAD(&disk_partitions);
for (p = 1; p <= MAX_SEARCH_PARTITIONS; p++) { ret = part_get_info(dev_desc, p, &info); @@ -294,6 +394,8 @@ static int set_gpt_info(struct blk_desc *dev_desc, return -1;
str = strdup(str_part); + if (str == NULL) + return -ENOMEM;
/* extract disk guid */ s = str; @@ -523,6 +625,86 @@ static int do_disk_guid(struct blk_desc *dev_desc, char * const namestr) return ret; }
+#ifdef CONFIG_CMD_GPT_FLIP +static int do_flip_gpt_parts(struct blk_desc *dev_desc) +{ + struct list_head *pos; + struct disk_part *curr; + disk_partition_t *new_partitions = NULL; + char disk_guid[UUID_STR_LEN + 1]; + char *partitions_list, *str_disk_guid; + u8 part_count = 0; + int partlistlen, ret, numparts = 0; + + ret = get_disk_guid(dev_desc, disk_guid); + if (ret < 0) + return ret; + + numparts = get_gpt_info(dev_desc); + if (numparts < 0) + return numparts; + printf("Current partition table with %d partitions is:\n", numparts); + print_gpt_info(); + + partlistlen = calc_parts_list_len(numparts); + partitions_list = (char *)malloc(partlistlen); + memset(partitions_list, '\0', partlistlen); + + ret = create_gpt_partitions_list(numparts, (const char *) disk_guid, + partitions_list); + if (ret < 0) + return ret; + debug("OLD partitions_list is %s with %d chars\n", partitions_list, strlen(partitions_list)); + + ret = set_gpt_info(dev_desc, (const char *)partitions_list, &str_disk_guid, + &new_partitions, &part_count); + if (ret < 0) + return ret; + + list_for_each(pos, &disk_partitions) { + curr = list_entry(pos, struct disk_part, list); + if (!strcmp((char *)curr->gpt_part_info.name, "backup_kernel")) + strcpy((char *)curr->gpt_part_info.name, "candidate_kernel"); + if (!strcmp((char *)curr->gpt_part_info.name, "primary_kernel")) + strcpy((char *)curr->gpt_part_info.name, "backup_kernel"); + if (!strcmp((char *)curr->gpt_part_info.name, "backup_rootfs")) + strcpy((char *)curr->gpt_part_info.name, "candidate_rootfs"); + if (!strcmp((char *)curr->gpt_part_info.name, "primary_rootfs")) + strcpy((char *)curr->gpt_part_info.name, "backup_rootfs"); + } + + ret = create_gpt_partitions_list(numparts, (const char *) disk_guid, partitions_list); + if (ret < 0) + return ret; + debug("NEW partitions_list is %s with %d chars\n", partitions_list, strlen(partitions_list)); + + ret = set_gpt_info(dev_desc, (const char *)partitions_list, &str_disk_guid, + &new_partitions, &part_count); + if (ret < 0) + return ret; + + debug("Writing new partition table\n"); + ret = gpt_restore(dev_desc, disk_guid, new_partitions, numparts); + if (ret < 0) { + printf("Writing new partition table failed\n"); + return ret; + } + + debug("Reading back new partition table\n"); + numparts = get_gpt_info(dev_desc); + if (numparts < 0) + return numparts; + printf("new partition table with %d partitions is:\n", numparts); + print_gpt_info(); + + del_gpt_info(); + free(partitions_list); + free(str_disk_guid); + free(new_partitions); + return ret; +} +#endif + /** * do_gpt(): Perform GPT operations * @@ -565,6 +747,10 @@ static int do_gpt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) return do_disk_guid(blk_dev_desc, argv[4]); } else if (strcmp(argv[1], "read") == 0) { return do_get_gpt_info(blk_dev_desc); +#ifdef CONFIG_CMD_GPT_FLIP + } else if (strcmp(argv[1], "flip") == 0) { + return do_flip_gpt_parts(blk_dev_desc); +#endif } else { return CMD_RET_USAGE; } @@ -596,4 +782,9 @@ U_BOOT_CMD(gpt, CONFIG_SYS_MAXARGS, 1, do_gpt, " Example usage:\n" " gpt guid mmc 0\n" " gpt guid mmc 0 varname\n" +#ifdef CONFIG_CMD_GPT_FLIP + "gpt partition-flip command\n" + "gpt flip <interface> <dev>\n" + " - exchange device's 'primary' and 'backup' partition names\n" +#endif ); diff --git a/doc/README.gpt b/doc/README.gpt index c0779a4..e29b188 100644 --- a/doc/README.gpt +++ b/doc/README.gpt @@ -210,6 +210,19 @@ Following line can be used to assess if GPT verification has succeed: U-BOOT> gpt verify mmc 0 $partitions U-BOOT> if test $? = 0; then echo "GPT OK"; else echo "GPT ERR"; fi
+Renaming GPT partitions from U-Boot: +==================================== + +GPT partition names are a mechanism via which userspace and U-Boot can +communicate about software updates and boot failure. The 'gpt guid', +'gpt read' and 'gpt flip' commands facilitate programmatic renaming of +partitions from bootscripts by generating and modifying the partitions +layout string. The code in gpt_flip() illustrates the case of +swapping 'primary' and 'backup' partitions via: + +U-BOOT> gpt flip mmc 0 + +Choose different partition names by modifying these strings in gpt.c.
Partition type GUID: ====================