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

Linux CMA代码分析

CMA全称Contiguous Memory Allocator,是Linux内核的连续内存分配器,最近就遇到一个因CMA分配失败导致的camera功能异常,log如下:<6>[ 3371.081458] alloc_contig_range: [8fa00, 8ff00) PFNs busy <6>[ 3371.081481] alloc_con...阅读全文

Android P重启卡死问题分析

最近遇到重启卡死的问题,有的是黑屏,有的是定屏在"正在重新启动"adb可用,高通平台。抓下logcat能发现如下log:ShutdownThread: Rebooting, reason: null代码在:/frameworks/base/services/core/java/com/android/server/power/ShutdownThread.java: ...阅读全文