arm

What does mrc p15 do in ARM inline assembly, and how does GNU C inline asm syntax work?

由 偶尔善良 提交于 2020-01-10 06:17:05
问题 what does this line in assembly arm does? mrc p15, 0, %0, c9, c13, 0" : : "r" (counter) who is p15 isn't it should be r15 what are all the others? what is :: who are c9, c1 what is the role of each argument? 回答1: Whilst MRC is a generic co-processor inter-op instruction, cp15 is the control processor - which all modern ARM CPUs have and this has been used by ARM was a means of extending the instruction set for on-chip units such as the cache, MMU, performance monitoring and lots else besides.

ARM linux开发之Ubuntu中NFS挂载配置，实现Ubuntu与ARM开发板的共享文件夹

由 六月ゝ 毕业季﹏ 提交于 2020-01-10 03:27:01
一、简介 NFS（Network File System，网络文件系统）是当前主流异构平台共享文件系统之一。 NFS可用于不同类型计算机、操作系统、网络架构和传输协议运行环境中的网络文件远程访问和共享。 总的来说，我们用它来实现Ubuntu和ARM开发板的文件共享 1.ubuntu：18.04 2.ARM开发板：linux系统 二、ubuntu上的配置 1.安装nfs服务器 linux@ubuntu:~$ sudo apt-get install nfs-kernel-server 2.建立一个文件夹用于共享（已经存在的文件夹也行） linux@ubuntu:~$ mkdir nfs 3.配置/etc/exports linux@ubuntu:~$ sudo vi /etc/exports 如图： 4.重启nfs服务器 linux@ubuntu:~$ sudo service nfs-kernel-server restart 查看是否重启成功 linux@ubuntu:~$ dmesg | tail -5 [18565.869903] NFSD: starting 90-second grace period (net f0000099) 重启完毕 三、ARM开发板配置 1.确保ARM开发板和Ubuntu都连接上网络，并且在同一网段 2.我的ubuntu的ip：192.168.2

M0+体系结构与指令系统简介

由 老子叫甜甜 提交于 2020-01-09 16:56:11
M0+体系结构与指令系统简介 ARM Cortex-M0+出现的背景 存储器映像 ARM Cortex-M0+指令集 数据传送类指令 取数指令 存数指令 寄存器间数据传送指令 堆栈操作指令 数据操作类指令 算术运算类指令 逻辑运算类指令 移位运算类指令 跳转指令 其他指令 ARM Cortex-M0+ 寻址方式 立即数寻址 寄存器寻址 偏移寻址及寄存器间接寻址 直接寻址 ARM Cortex-M0+出现的背景 32位的M0+系列处理器是ARM公司2012年推出的，主要的目的是替代原有的8位/16位微控制器，具有性价比高，功耗低等特点，其内核性能接近8位或16位竞争产品的2倍。 这些功能模块提高了M0+处理器的性能及其编程优势，降低了系统的移植难度。 存储器映像 把这4GB空间当作存储器来看待，分成若干区间，都可安排一些实际的物理资源。 用于标志ALU的状态：负标志N 零标志Z 进位标志C 溢出标志V 异常号 中断屏蔽寄存器，只有D0位有意义，当该位被置位时，除不可屏蔽中断和硬件错误以外的所有中断都被屏蔽。 ARM Cortex-M0+指令集 数据传送类指令 取数指令 存数指令 寄存器间数据传送指令 堆栈操作指令 数据操作类指令 算术运算类指令 逻辑运算类指令 移位运算类指令 跳转指令 控制程序的执行流程 其他指令 ARM Cortex-M0+ 寻址方式 立即数寻址

Run arm docker image on X86 through (Docker hub image)/multiarch/qemu-user-static

由 非 Y 不嫁゛ 提交于 2020-01-09 13:47:04
jhula@ShSwDev2:~/local/edgex/test-linux-docker-lake/myhello$ docker run --rm --privileged multiarch/qemu-user-static:register --reset Unable to find image 'multiarch/qemu-user-static:register' locally register: Pulling from multiarch/qemu-user-static bdbbaa22dec6: Pull complete 42399a41a764: Pull complete ed8a5179ae11: Pull complete 1ec39da9c97d: Pull complete Digest: sha256:7502ce31890ab5da0ab6e5e5edc1e2563caa45da1c5d76aaf7dc4252aea926dc Status: Downloaded newer image for multiarch/qemu-user-static:register Setting /usr/bin/qemu-alpha-static as binfmt interpreter for alpha Setting /usr/bin

Endianness conversion in ARM

由 泄露秘密 提交于 2020-01-09 10:04:31
问题 How do I convert big endian to little endian in ARM? 回答1: Are you talking about ARM's endian modes, or reading something written by some other big endian processor, etc? Normally converting to/from big/little endian you swap the bytes around. So 0xABCD is 0xCDAB when viewed as a 16 bit number 0x12345678 is 0x78563412 when viewed as a 32 bit number. ARM cores armv5 and older (ARM7, ARM9, etc) have an endian mode known as BE-32, meaning big endian word invariant. armv6 and newer (mpcore, cortex

Endianness conversion in ARM

由 随声附和 提交于 2020-01-09 10:04:28
问题 How do I convert big endian to little endian in ARM? 回答1: Are you talking about ARM's endian modes, or reading something written by some other big endian processor, etc? Normally converting to/from big/little endian you swap the bytes around. So 0xABCD is 0xCDAB when viewed as a 16 bit number 0x12345678 is 0x78563412 when viewed as a 32 bit number. ARM cores armv5 and older (ARM7, ARM9, etc) have an endian mode known as BE-32, meaning big endian word invariant. armv6 and newer (mpcore, cortex

Endianness conversion in ARM

由 你。 提交于 2020-01-09 10:03:12
问题 How do I convert big endian to little endian in ARM? 回答1: Are you talking about ARM's endian modes, or reading something written by some other big endian processor, etc? Normally converting to/from big/little endian you swap the bytes around. So 0xABCD is 0xCDAB when viewed as a 16 bit number 0x12345678 is 0x78563412 when viewed as a 32 bit number. ARM cores armv5 and older (ARM7, ARM9, etc) have an endian mode known as BE-32, meaning big endian word invariant. armv6 and newer (mpcore, cortex

ARM and NEON can work in parallel?

由 谁都会走 提交于 2020-01-09 09:16:06
问题 This is with reference to question: Checksum code implementation for Neon in Intrinsics Opening the sub-questions listed in the link as separate individual questions. As multi questions aren't to be asked as a part of single thread. Anyway coming to the question: Can ARM and NEON (speaking in terms of arm cortex-a8 architecture) actually work in parallel? How can I achieve this? Could someone point to me or share some sample implementations(pseudo-code/algorithms/code, not the theoretical

How to single step ARM assembly in GDB on QEMU?

由 孤者浪人 提交于 2020-01-09 05:25:07
问题 I'm trying to learn about ARM assembler programming using the GNU assembler. I've setup my PC with QEmu and have a Debian ARM-HF chroot environment. If I assemble and link my test program: .text .global _start _start: mov r0, #6 bx lr with: as test.s -o test.o ld test.o -o test Then load the file into gdb and set a breakpoint on _start: root@Latitude-E6420:/root# gdb test GNU gdb (GDB) 7.6.1 (Debian 7.6.1-1) Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3

How to work with external libraries when cross compiling?

由 落花浮王杯 提交于 2020-01-09 04:18:05
问题 I am writing some code for raspberry pi ARM target on x86 ubuntu machine. I am using the gcc-linaro-armhf toolchain. I am able to cross compile and run some independent programs on pi. Now, I want to link my code with external library such as ncurses. How can I achieve this. Should I just link my program with the existing ncurses lib on host machine and then run on ARM? (I don't think this will work) Do I need to get source or prebuilt version of lib for arm, put it in my lib path and then
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