v1_EN_SrsLinuxArm

SRS for linux-arm

How to run SRS on ARM pcu?

• Application on ARM to publish stream to SRS, use srs-librtmp.
• ARM directly publish h.264 stream to SRS(Not support yet).
• Run SRS on ARM: Client can play strema on ARm.

Why run SRS on ARM?

The use scenario:

• There are lots of ARM device, and the center server cannot accept so many streams.
• User can directly play stream on ARM when ARM running SRS server.
• SRS can output RTMP and HLS, for both PC and mobile(Android+IOS).

Ubuntu Cross Build SRS

Install the ARM cross build tool for SRS:

sudo aptitude install -y gcc-arm-linux-gnueabi g++-arm-linux-gnueabi

The tools compare:

x86	armhf(v7cpu)
gcc	arm-linux-gnueabi-gcc
g++	arm-linux-gnueabi-g++
ar	arm-linux-gnueabi-ar
as	arm-linux-gnueabi-as
ld	arm-linux-gnueabi-ld
ranlib	arm-linux-gnueabi-ranlib
strip	arm-linux-gnueabi-strip

Cross build:

./configure --with-arm-ubuntu12 && make

The bellow features can used for ARM-SRS:

• --with-arm-ubuntu12: To use the cross build tools for ubuntu.
• --with-ssl: To support complex handshake, read Handshake
• --with-hls: To support HLS.
• --with-http-server: To support embeded server to delivery HLS, read SRS HTTP SERVER。
• --with-http-api: To support http api, read http api。
• --with-librtmp: The client library.

Copy the binary to ARM and run:

winlin@winlin-VirtualBox:~/srs$ file objs/srs
objs/srs: ELF 32-bit LSB executable, ARM, version 1 (SYSV), statically linked, 
for GNU/Linux 2.6.31, BuildID[sha1]=0xfba434cea50d6b02fd6e21ce67f01c39772c724b, 
not stripped

Use Other Cross build tools

SRS supports to modify the Default cross build tools:

• Modify the configure then build.
• Export evn variables, then build.

Modify the configure：

SrsArmCC="arm-linux-gnueabi-gcc"
SrsArmGCC="arm-linux-gnueabi-gcc"
SrsArmCXX="arm-linux-gnueabi-g++"
SrsArmAR="arm-linux-gnueabi-ar"
SrsArmLD="arm-linux-gnueabi-ld"
SrsArmRANDLIB="arm-linux-gnueabi-ranlib"

Then configure and build:

./configure --with-arm-ubuntu12 --with-ssl --with-hls --with-librtmp && make

Export env variables

export SrsArmCC="arm-linux-gnueabi-gcc" &&
export SrsArmGCC="arm-linux-gnueabi-gcc" &&
export SrsArmCXX="arm-linux-gnueabi-g++" &&
export SrsArmAR="arm-linux-gnueabi-ar" &&
export SrsArmLD="arm-linux-gnueabi-ld" &&
export SrsArmRANDLIB="arm-linux-gnueabi-ranlib" &&
./configure --with-arm-ubuntu12 --with-ssl --with-hls --with-librtmp && make

RaspberryPi

SRS can be build on ARM os, for example, raspbian:

• Install the lsb_release, which is used by package: sudo aptitude install -y lsb_release
• Install zip, for package: sudo aptitude install -y zip
• Build SRS: ./configure --pi && make
• Package SRS: ./scripts/package.sh --pi

The package, for instance, objs/SRS-RaspberryPi7-armv6l-0.9.37.zip, can be unzip and install.

Armel and Armhf

The error Illegal instruction is the cpu not compatible, the cross build target cpu too high, read http://stackoverflow.com/questions/14253626/arm-cross-compiling

The bellow is a simple test program:

/*
 arm-linux-gnueabi-g++ -o test test.cpp -static
 arm-linux-gnueabi-strip test
*/
#include <stdio.h>

int main(int argc, char** argv) {
    printf("hello, arm!\n");
    return 0;
}

To get the target cpu:

arm-linux-gnueabi-readelf --file-header --arch-specific test
Result:
  Machine:                           ARM
File Attributes
  Tag_CPU_name: "7-A"
  Tag_CPU_arch: v7

So, the ubuntu12 cross build target cpu is cpuv7(debian armhf).

The debian armel, cpu is armv5:

root@debian-armel:~# cat /proc/cpuinfo 
Processor	: ARM926EJ-S rev 5 (v5l)
CPU revision	: 5

While the debian armhf, cpu is armv7:

root@debian-armhf:~# cat /proc/cpuinfo 
Processor	: ARMv7 Processor rev 0 (v7l)
CPU architecture: 7

Run test program on armhf:

root@debian-armhf:~# ./test 
hello, arm!

The SRS License for ARM

SRS is MIT license, ok for ARM.

ST-ARM-BUG-FIX

I fixed a bug for ARM in st, the setjmp.h layout changed:

• i386 offset of sp is 4：env[0].__jmp_buf[4]=(long)sp
• x86_64 offset of sp is 6：env[0].__jmp_buf[6]=(long)sp
• armhf(v7cpu) sp offset is 8, but st use 20.

Read bug #182, bug #190

// md.h
        #elif defined(__i386__)
            #if defined(__GLIBC__) && __GLIBC__ >= 2
                #define MD_GET_SP(_t) (_t)->context[0].__jmpbuf[4]
        #elif defined(__amd64__) || defined(__x86_64__)
            #define MD_GET_SP(_t) (_t)->context[0].__jmpbuf[6]
        #elif defined(__arm__)
            #if defined(__GLIBC__) && __GLIBC__ >= 2
                #define MD_GET_SP(_t) (_t)->context[0].__jmpbuf[20]

When st_init(), we should never fork process, read bug #190

Winlin 2014.11