cmd: gpt: Add option to write GPT partitions to environment variable

This change would enhance the existing 'gpt read' command to allow
(optionally) writing of the read GPT partitions to an environment
variable in the UBOOT partitions layout format. This would allow users
to easily change the overall partition settings by editing said variable
and then using the variable in the 'gpt write' and 'gpt verify' commands.

Signed-off-by: Farhan Ali <farhan.ali@broadcom.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Corneliu Doban <cdoban@broadcom.com>
Cc: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/doc/README.gpt b/doc/README.gpt
index ac975f6..91e397d 100644
--- a/doc/README.gpt
+++ b/doc/README.gpt
@@ -237,6 +237,23 @@ doc/arch/index.rst:
 => gpt swap host 0 name othername
 [ . . . ]
 
+Modifying GPT partition layout from U-Boot:
+===========================================
+
+The entire GPT partition layout can be exported to an environment
+variable and then modified enmasse. Users can change the partition
+numbers, offsets, names and sizes. The resulting variable can used to
+reformat the device. Here is an example of reading the GPT partitions
+into a variable and then modifying them:
+
+U-BOOT> gpt read mmc 0 current_partitions
+U-BOOT> env edit current_partitions
+edit: uuid_disk=[...];name=part1,start=0x4000,size=0x4000,uuid=[...];
+name=part2,start=0xc000,size=0xc000,uuid=[...];[ . . . ]
+
+U-BOOT> gpt write mmc 0 $current_partitions
+U-BOOT> gpt verify mmc 0 $current_partitions
+
 Partition type GUID:
 ====================