u-boot/doc/README.gpt

13 - GPT (GUID Partition Table) - it is the EFI standard part
19 This document describes the GPT partition table format and usage of
20 the gpt command in u-boot.
25 GPT for marking disks/partitions is using the UUID. It is supposed to be a
42 GPT brief explanation:
51 	LBA 1          |Primary GPT Header               | Primary
52 	-------------------------------------------------- GPT
69 	-------------------------------------------------- GPT
75 	LBA -1         |Backup GPT Header                |
78 For a legacy reasons, GPT's LBA 0 sector has a MBR structure. It is called
81 handling the GPT sees it as a storage device without free space.
88 Primary/Backup GPT header:
115 GPT headers and partition entries are protected by CRC32 (the POSIX CRC32).
117 Primary GPT header and Backup GPT header have swapped values of "Current LBA"
120 CRC32 for GPT headers (field "CRC of header") are calculated up till
127 Observe, how Backup GPT is placed in the memory. It is NOT a mirror reflect
151 Creating GPT partitions in U-Boot:
172    the generated UUID.  The 'gpt guid' command reads the current value of the
173    uuid_disk from the GPT.
175    The field 'bootable' is optional, it is used to mark the GPT partition
185    gpt write mmc 0 $partitions
187 Checking (validating) GPT partitions in U-Boot:
193    gpt verify mmc 0 [$partitions]
197 When it is not provided, only basic checks based on CRC32 calculation for GPT
204 on non-volatile medium stored GPT.
206 Following line can be used to assess if GPT verification has succeed:
208 U-BOOT> gpt verify mmc 0 $partitions
209 U-BOOT> if test $? = 0; then echo "GPT OK"; else echo "GPT ERR"; fi
211 Renaming GPT partitions from U-Boot:
214 GPT partition names are a mechanism via which userspace and U-Boot can
215 communicate about software updates and boot failure.  The 'gpt guid',
216 'gpt read', 'gpt rename' and 'gpt swap' commands facilitate
221 U-BOOT> gpt swap mmc 0 primary backup
228 U-BOOT> gpt rename mmc 0 1 primary
230 The GPT functionality may be tested with the 'sandbox' board by
235 => gpt read host 0
237 => gpt swap host 0 name othername
280 Two programs, namely: 'gdisk' and 'parted' are recommended to work with GPT
293 also stored in big endian in disk GPT.