How to build mkfs.erofs for ARM64

mkfs.erofs is a user-space tool to create erofs filesystem images.erofs是华为为了增强安卓性能提出的自研文件系统,其内核文档提到用户态工具:The following git tree provides the file system user-spacetools under development ...阅读全文

如何测试cpufreq setpolicy driver

上一篇说过有个cpufreq setpolicy patch涉及验证,qemu intel_pstate是不行了,主要是不支持X86_FEATURE_HWP or X86_FEATURE_APERFMPERF,只能在物理机上测试了。我的本本是E40(一代i3),用了有点久了也不支持,intel_pstate是for SandyBridge arch,Intel从二代 i3...阅读全文

如何用QEMU运行x86 kernel

最近在提交cpufreq patch,稍微有点逻辑改动的Rafael都要你test, test。有个改动涉及setpolicy driver,要验证,第一印象就是用qemu。让我们来看下如何搭环境(initrd=ramdisk):my linux server(xeon) for building can not access internet,also vb under...阅读全文

CPUFreq policy代码分析

参考4.9,主要了解几个结构成员:struct cpufreq_policy { /* CPUs sharing clock, require sw coordination */ cpumask_var_t cpus; /* Online CPUs only */ cpumask_var_t related_cp...阅读全文

CPUFreq boost代码分析

参考4.9内核,还是先看文档描述:IntroductionSome CPUs support a functionality to raise the operating frequency ofsome cores in a multi-core package if certain conditions apply, mostlyif the whole chip i...阅读全文

Linux CPUFreq Subsystem Overview

参考4.9,CPUFreq即CPU Frequency scaling或者CPU performance scaling,允许你运行时改变CPU clock speed.文档路径: ./Documentation/cpu-freq/,先来看几个概念:Some CPU frequency scaling-capable processor switch between va...阅读全文