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Diffstat (limited to 'doc/README.ubi')
| -rw-r--r-- | doc/README.ubi | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/doc/README.ubi b/doc/README.ubi index 9efab6cdc9..c78a81795b 100644 --- a/doc/README.ubi +++ b/doc/README.ubi @@ -223,3 +223,36 @@ For example: => ubifsumount Unmounting UBIFS volume recovery! + + +Usage of the UBI CRC skip-check flag of static volumes: +------------------------------------------------------- +Some users of static UBI volumes implement their own integrity check, +thus making the volume CRC check done at open time useless. For +instance, this is the case when one use the ubiblock + dm-verity + +squashfs combination, where dm-verity already checks integrity of the +block device but this time at the block granularity instead of verifying +the whole volume. + +Skipping this test drastically improves the boot-time. + +U-Boot now supports the "skip_check" flag to optionally skip the CRC +check at open time. + +Usage: Case A - Upon UBI volume creation: +You can optionally add "--skipcheck" to the "ubi create" command: + +ubi create[vol] volume [size] [type] [id] [--skipcheck] + - create volume name with size ('-' for maximum available size) + +Usage: Case B - With an already existing UBI volume: +Use the "ubi skipcheck" command: + +ubi skipcheck volume on/off - Set or clear skip_check flag in volume header + +Example: +=> ubi skipcheck rootfs0 on +Setting skip_check on volume rootfs0 + +BTW: This saves approx. 10 seconds Linux bootup time on a MT7688 based +target with 128MiB of SPI NAND. |