X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=doc%2FREADME.gpt;h=facd7afc3acdb70560096d3cdc417a68b734ae3f;hb=19096aba4f90d064e0f6327eeedce6b90f0aefd6;hp=0a3286f63686c4de9e09f76c94cd176cc0514bdc;hpb=0a242386254066b45a9ab6dbdfa902575402df9b;p=oweals%2Fu-boot.git diff --git a/doc/README.gpt b/doc/README.gpt index 0a3286f636..facd7afc3a 100644 --- a/doc/README.gpt +++ b/doc/README.gpt @@ -1,10 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0+ # # Copyright (C) 2012 Samsung Electronics # # Lukasz Majewski -# -# -# SPDX-License-Identifier: GPL-2.0+ Glossary: ======== @@ -171,7 +169,8 @@ To restore GUID partition table one needs to: The fields 'uuid' and 'uuid_disk' are optional if CONFIG_RANDOM_UUID is enabled. A random uuid will be used if omitted or they point to an empty/ non-existent environment variable. The environment variable will be set to - the generated UUID. + the generated UUID. The 'gpt guid' command reads the current value of the + uuid_disk from the GPT. The field 'bootable' is optional, it is used to mark the GPT partition bootable (set attribute flags "Legacy BIOS bootable"). @@ -209,15 +208,33 @@ 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', 'gpt rename' and 'gpt swap' commands facilitate +programmatic renaming of partitions from bootscripts by generating and +modifying the partitions layout string. Here is an illustration of +employing 'swap' to exchange 'primary' and 'backup' partition names: + +U-BOOT> gpt swap mmc 0 primary backup + +Afterwards, all partitions previously named 'primary' will be named +'backup', and vice-versa. Alternatively, single partitions may be +renamed. In this example, mmc0's first partition will be renamed +'primary': + +U-BOOT> gpt rename mmc 0 1 primary The GPT functionality may be tested with the 'sandbox' board by creating a disk image as described under 'Block Device Emulation' in -board/sandbox/README.sandbox: +doc/arch/index.rst: =>host bind 0 ./disk.raw => gpt read host 0 [ . . . ] -=> gpt flip host 0 +=> gpt swap host 0 name othername [ . . . ] Partition type GUID: