EROFS on-disk compact index 生成分析
compact index是EROFS默认使用的压缩布局，内核提交描述如下： staging: erofs: add compacted ondisk compression indexes
This patch introduces new compacted compression indexes.
In contract to legacy...阅读全文
2021年
qemu和host间传输文件方法之挂载
我们有时希望传输文件到qemu里，那如何做了？官方给的答复：Simple: Treat the virtual machine as if it was a real machine andtransfer files to and from it.More to the point, the following are the most common methods:A...阅读全文
转：如何在EROFS上支持Android文件块映射
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
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)
{
...
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e-Paper Weather Station
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
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
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
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