TJ的技术博客

转：如何在EROFS上支持Android文件块映射

2021-10-16 | File System - erofs | 评论 | 浏览 (214)

本文首先从Ext4认识Android文件块映射，然后从生成EROFS文件系统的三个部分(非压缩文件、压缩文件和尾端数据)分析如何生成block list文件。阅读全文

Read squashfs readpage() code

2021-08-09 | File System - squashfs | 评论 | 浏览 (365)

内核参考5.x:const struct address_space_operations squashfs_aops = { .readpage = squashfs_readpage };static int squashfs_readpage(struct file *file, struct page *page) { ... ...阅读全文

e-Paper Weather Station

2021-07-31 | IoT - e-paper | 评论 | 浏览 (320)

I always want to use the 7.5 e-Paper(i already have) to display weather forecast instead of my previous solution displayed on LCD. You know, the old one is not beautiful for me any more s...阅读全文

erofs-utils mkfs 概览

2021-06-17 | File System - erofs-utils | 评论 | 浏览 (538)

参考erofs-utils 1.2.1, 入口是erofs_mkfs_build_tree(), 不关注xattr/extent, 看之前我们再了解下inode:Inodes store information about files and directories (folders), such as file ownership, access mode (read,...阅读全文

eMMC CMDQ 超时分析

2021-05-13 | Device Driver - CMDQ | 评论 | 浏览 (677)

先看HW架构CQE: Command Queueing Engine，负责管理software和eMMC device的data传输。首先CQE接收来自SW的task(via TDL和doorbell)，接下来的command flows主要有三步：Step1. Queuing a Transaction(CMD44+CMD45)CQE发出CMD44/CMD45给eMMC...阅读全文

UFS Write Booster 分析

2021-03-10 | Device Driver - WriteBooster | 评论 | 浏览 (1,242)

先来看看JEDEC有关WriteBooster(WB)的描述：TLC NAND比SLC NAND慢的原因就是TLC里面有更多的programming steps。ok，为了提高性能，那就把TLC NAND的一部分配置成SLC NAND不就行了。rt，WriteBooster特性由此而来，就是把这部分SLC NAND用作WriteBooster Buffer。有个概率图： ...阅读全文