x86: apl: Use devicetree for FSP-M configuration

[oweals/u-boot.git] / doc / README.ubi

diff --git a/doc/README.ubi b/doc/README.ubi
index 3cf4ef232d3883b5451ec992c543689f3f24ccab..c78a81795b92554b8771350650fb33ba3608ea8a 100644 (file)
--- a/doc/README.ubi
+++ b/doc/README.ubi
@@ -14,6 +14,8 @@ ubi part [part] [offset]
 ubi info [l[ayout]] - Display volume and ubi layout information
 ubi create[vol] volume [size] [type] - create volume name with size
 ubi write[vol] address volume size - Write volume from address with size
+ubi write.part address volume size [fullsize]
+ - Write part of a volume from address
 ubi read[vol] address volume [size] - Read volume to address with size
 ubi remove[vol] volume - Remove volume
 [Legends]
@@ -77,6 +79,7 @@ ubi createvol Create UBI volume on UBI device
 ubi removevol  Remove UBI volume from UBI device
 ubi read       Read data from UBI volume to memory
 ubi write      Write data from memory to UBI volume
+ubi write.part Write data from memory to UBI volume, in parts
 
 
 Here a few examples on the usage:
@@ -185,8 +188,8 @@ ubifsls [directory]
 For example:
 
 => ubifsls
-            17442  Thu Jan 01 02:57:38 1970  imx28-evk.dtb
-          2998146  Thu Jan 01 02:57:43 1970  zImage
+           17442  Thu Jan 01 02:57:38 1970  imx28-evk.dtb
+         2998146  Thu Jan 01 02:57:43 1970  zImage
 
 
 And the ubifsload command allows you to load a file from a UBI
@@ -220,3 +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.