一 ubi管理下的SLC nand
refer to
http://www.linux-mtd.infradead.org/doc/ubi.html
http://www.360doc.com/content/12/0305/19/1317564_192019619.shtml
1
對于K9K8G08U0A (1GB SLC），


2.
假如對tiny6410的SLC 1G核心板的nand 的MTD分區(qū)如下，


3.
在58 0000 - 4000 0000的mtd分區(qū)之上，假如僅人為劃分了一個UBI Volume(默認(rèn)還有一個內(nèi)部卷)，ubi管理下的這個mtd結(jié)構(gòu)如下，
(假設(shè)沒有子頁)

說明：
PEB physical eraseblock 物理擦除塊，即nand的最小擦除單位，為64個頁，131072B。
LEB logical eraseblock 邏輯擦除塊，是ubi 卷里的概念，是對物理擦除塊的映射，但不包含物理擦除塊最前面的EC頭頁和VID頭頁。所以是62個頁,126976B。
???
erase counter header (or EC header) which contains the erase counter of the physical eraseblock (PEB) plus some other not so important information
volume identifier header (or VID header) which stores volume ID and logical eraseblock (LEB) number thisPEB belongs to (plus some other not so important information).

layout volume 也就是mtd分區(qū)的卷表所在的卷，包括兩個LEB，但內(nèi)容一致。
Volume table is an on-flash data structure which contains information about each volume on this UBI device
Internally, the volume table resides in a special-purpose UBI volume which is calledlayout volume

一個mtd分區(qū)下可以建好多ubi卷，但不能超過128個。

ubi管理下的nand的額外開銷：
2 PEBs are used to store the volume table;
1 PEB is reserved for wear-leveling purposes;
1 PEB is reserved for the atomic LEB change operation;
some amount of PEBs is reserved for bad PEB handling; this is applicable for NAND flash, but not for NOR flash; the amount of reserved PEBs is configurable and is equal to 20 blocks per 1024 blocks by default;
UBI stores the EC and VID headers at the beginning of each PEB; the amount of bytes used for these purposes depends on the flash type and is explained below.

在flash說明書上也有塊圖，里面的塊就是PEB,每個PEB去掉page 0,1就可以被映射為一個LEB

轉(zhuǎn)載于:https://www.cnblogs.com/-song/archive/2012/12/06/3331837.html

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