Using gdbserver to debug MDM9xxx

openembedded提供了一個良好的gdb環境，設定步驟如下。

brook@vista:/home/brook/apps_proc/poky/build$ tar zxvf tmp-glibc/deploy/images/mdm9607/machine-image-mdm9607-dbg.tar.gz
./
./var/
./var/lib/
./var/lib/opkg/
./var/lib/opkg/info/
...

brook@vista:/home/brook/apps_proc/poky/build$ mv usr/lib/.debug/* usr/lib/
brook@vista:/home/brook/apps_proc/poky/build$ mv lib/.debug/* lib

brook@vista:/home/brook/apps_proc/poky/build$ ln -s libconfig.so.9.2.0 usr/lib/libconfig.so.9
...

brook@vista:/home/brook/apps_proc/poky/build$ ln -s libpthread-2.22.so lib/libpthread.so.0
brook@vista:/home/brook/apps_proc/poky/build$ ln -s librt-2.22.so lib/librt.so.1
brook@vista:/home/brook/apps_proc/poky/build$ ln -s libm-2.22.so lib/libm.so.6
brook@vista:/home/brook/apps_proc/poky/build$ ln -s libc-2.22.so lib/libc.so.6
brook@vista:/home/brook/apps_proc/poky/build$ ln -s ld-2.22.so lib/ld-linux.so.3
brook@vista:/home/brook/apps_proc/poky/build$ ln -s libdl-2.22.so lib/libdl.so.2
...

brook@vista:/home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/build/src$ adb push myprog /usr/bin/myprog

brook@vista:/home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/build/src$ adb shell
sh-3.2# gdbserver :2345 /usr/bin/myprog
Process /usr/bin/myprog created; pid = 9035
Listening on port 2345

接著host端就可以開啟GDB來debug了

brook@vista:/home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/build/src$ arm-oe-linux-gnueabi-gdb myprog 
GNU gdb (GDB) 7.10.1
Copyright (C) 2015 Free Software Foundation, Inc.
...
Reading symbols from myprog...done.
(gdb) set sysroot /home/brook/apps_proc/poky/build/
(gdb) target remote 10.0.0.1:2345
Remote debugging using 10.0.0.1:2345
Reading symbols from /home/brook/apps_proc/poky/build//lib/ld-linux.so.3...done.
0xb6fceac0 in ?? ()
(gdb) b main
Breakpoint 1 at 0x7f5595ac: file /home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/src/main.c, line 207.
(gdb) c
Continuing.

Breakpoint 1, main (argc=1, argv=0xbefffdf4)
    at /home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/src/main.c:207
207     {
(gdb) set sysroot /home/brook/apps_proc/poky/build
warning: .dynamic section for "/home/brook/apps_proc/poky/build/lib/libpthread.so.0" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/home/brook/apps_proc/poky/build/lib/libm.so.6" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/home/brook/apps_proc/poky/build/lib/libc.so.6" is not at the expected address (wrong library or version mismatch?)
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"?
Reading symbols from /home/brook/apps_proc/poky/build/usr/lib/libconfig.so.9...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/libpthread.so.0...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/librt.so.1...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/libm.so.6...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/libc.so.6...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/libdl.so.2...done.
(gdb) info share
From        To          Syms Read   Shared Object Library
0x7473e7c0  0x7475a328  Yes         /home/brook/apps_proc/poky/build/lib/ld-linux.so.3
0xb6fc42d0  0xb6fca6e0  Yes         /home/brook/apps_proc/poky/build/usr/lib/libconfig.so.9
0xb6ebc210  0xb6ecb4e8  Yes         /home/brook/apps_proc/poky/build/lib/libpthread.so.0
0xb6ea2720  0xb6ea6034  Yes         /home/brook/apps_proc/poky/build/lib/librt.so.1
0xb6e28bf0  0xb6e5ac20  Yes         /home/brook/apps_proc/poky/build/lib/libm.so.6
0xb6ced280  0xb6dee638  Yes         /home/brook/apps_proc/poky/build/lib/libc.so.6
0xb6cc3928  0xb6cc4870  Yes         /home/brook/apps_proc/poky/build/lib/libdl.so.2

確認所有symbol都有找到之後, 就可以開始debug之旅了.

Note for Yocto Project Reference Manual v2.4 - ch8.141 update-alternatives.bbclass

當有多個recipes提供相同的命令時, update-alternatives.bbclass可以幫你做替代("alternative"), 例如，可以從busybox，binutils和elfutils中使用ar命令。 update-alternatives.bbclass會幫你重新命名，以便安裝多個package而不會發生衝突。無論安裝或隨後刪除哪些package，ar命令仍然有效。
要使用update-alternatives.bbclass，你需要為這個package定義一些變量：
ALTERNATIVE_ = "name1 name2 name3 ..."
列出所有這個package的alternatives指令

設定name這個命令的link的路徑
ALTERNATIVE_LINK_NAME[name] = "target"

設定該package的預設priority，數值越大，priority越高
ALTERNATIVE_PRIORITY

針對特定命令另外設定priority，數值越大，priority越高
ALTERNATIVE_PRIORITY[name] = "20"

範例

brook這個package的檔案結構

brook@vista:~/oe-core/meta/recipes-devtools/brook$ tree
.
|-- brook-1.0.0
|   |-- brookbox
|   |-- copyright
|   `-- insmod
`-- brook_1.0.0.bb

1 directory, 4 files

brookbox類似busybox，後面會有多個檔案link到該檔案，而insmod是一個獨立檔案

brook_1.0.0.bb

SUMMARY = "Brook demo update-alternatives"
DESCRIPTION = "This package is used for Brook to demo update-alternatives"
LICENSE = "GPLv2+"
LIC_FILES_CHKSUM = "file://${WORKDIR}/copyright;md5=afcc69d729fbf1d0a2af28ce44a23991 \
"
SRC_URI = "file://insmod \
        file://copyright \
        file://brookbox \
"
inherit update-alternatives

ALTERNATIVE_${PN} = "insmod route reboot shutdown poweroff"
ALTERNATIVE_PRIORITY = "100"

ALTERNATIVE_LINK_NAME[insmod] = "${base_sbindir}/insmod"
ALTERNATIVE_PRIORITY[insmod] = "50"

ALTERNATIVE_LINK_NAME[route] = "${base_sbindir}/route"
ALTERNATIVE_PRIORITY[route] = "50"

ALTERNATIVE_LINK_NAME[reboot] = "${base_sbindir}/reboot"

ALTERNATIVE_LINK_NAME[shutdown] = "${base_sbindir}/shutdown"
ALTERNATIVE_PRIORITY[shutdown] = "10"

ALTERNATIVE_LINK_NAME[poweroff] = "${base_sbindir}/poweroff"
ALTERNATIVE_PRIORITY[poweroff] = "500"

do_install () {
        install -d                              ${D}${base_sbindir}
        install -m 0755    ${WORKDIR}/insmod    ${D}${base_sbindir}/insmod
        install -m 0755    ${WORKDIR}/brookbox  ${D}${base_sbindir}/brook
        ln -s ${base_sbindir}/brook ${D}${base_sbindir}/route
        ln -s ${base_sbindir}/brook ${D}${base_sbindir}/reboot
        ln -s ${base_sbindir}/brook ${D}${base_sbindir}/shutdown
        ln -s ${base_sbindir}/brook ${D}${base_sbindir}/poweroff
}

sysvinit也同時註冊了reboot，shutdown與poweroff，其priority都是200，而這裡的priority分別為100，10，500，所以最後結果如下

brook@vista:~/oe-core/build/tmp-glibc/work/oe-linux-gnueabi/image/1.0-r0/rootfs$ ls -al sbin/|grep brook
-rwxr-xr-x  1 jenkins jenkins      6 Dec  9 22:17 brook
lrwxrwxrwx  1 jenkins jenkins     18 Dec  9 22:17 insmod -> /sbin/insmod.brook
-rwxr-xr-x  1 jenkins jenkins      6 Dec  9 22:17 insmod.brook
lrwxrwxrwx  1 jenkins jenkins     20 Dec  9 22:17 poweroff -> /sbin/poweroff.brook
lrwxrwxrwx  1 jenkins jenkins     11 Dec  9 22:17 poweroff.brook -> /sbin/brook
lrwxrwxrwx  1 jenkins jenkins     11 Dec  9 22:17 reboot.brook -> /sbin/brook
lrwxrwxrwx  1 jenkins jenkins     17 Dec  9 22:17 route -> /sbin/route.brook
lrwxrwxrwx  1 jenkins jenkins     11 Dec  9 22:17 route.brook -> /sbin/brook
lrwxrwxrwx  1 jenkins jenkins     11 Dec  9 22:17 shutdown.brook -> /sbin/brook

reboot與shutdown都小於sysvinit，所以不適用brook，poweroff高於sysvinit，所以使用brook這個package提供的命令

參考資料:
• Yocto Project Reference Manual 2.4

Install Node.js on Openembedded

基本上Node.js在Openembedded上的recipes都已經寫好了，只要clone下來，並且加入IMAGE_INSTALL列表即可

brook@vista:~/projects/poky$ git clone https://github.com/imyller/meta-nodejs.git
Cloning into 'meta-nodejs'...
remote: Counting objects: 1575, done.
remote: Compressing objects: 100% (14/14), done.
remote: Total 1575 (delta 9), reused 0 (delta 0), pack-reused 1561
Receiving objects: 100% (1575/1575), 241.91 KiB | 368.00 KiB/s, done.
Resolving deltas: 100% (846/846), done.
Checking connectivity... done.
brook@vista:~/projects/poky$ . oe-init-build-env
You had no conf/local.conf file. This configuration file has therefore been
created for you with some default values. You may wish to edit it to, for
example, select a different MACHINE (target hardware). See conf/local.conf
for more information as common configuration options are commented.

You had no conf/bblayers.conf file. This configuration file has therefore been
created for you with some default values. To add additional metadata layers
into your configuration please add entries to conf/bblayers.conf.

The Yocto Project has extensive documentation about OE including a reference
manual which can be found at:
    http://yoctoproject.org/documentation

For more information about OpenEmbedded see their website:
    http://www.openembedded.org/


### Shell environment set up for builds. ###

You can now run 'bitbake <target>'

Common targets are:
    core-image-minimal
    core-image-sato
    meta-toolchain
    meta-ide-support

You can also run generated qemu images with a command like 'runqemu qemux86'

brook@vista:~/projects/poky/build$ vim conf/bblayers.conf
...下段說明
brook@vista:~/projects/poky/build$ vim conf/local.conf
...下段說明
brook@vista:~/projects/poky/build$ bitbake core-image-minimal
WARNING: Host distribution "Ubuntu-16.04" has not been validated with this version of the build system; you may possibly experience unexpected failures. It is recommended that you use a tested distribution.
Parsing recipes: 100% |#############################################################################################| Time: 00:00:28
Parsing of 876 .bb files complete (0 cached, 876 parsed). 1316 targets, 49 skipped, 0 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies

Build Configuration:
BB_VERSION        = "1.30.0"
BUILD_SYS         = "x86_64-linux"
NATIVELSBSTRING   = "Ubuntu-16.04"
TARGET_SYS        = "i586-poky-linux"
MACHINE           = "qemux86"
DISTRO            = "poky"
DISTRO_VERSION    = "2.1.1"
TUNE_FEATURES     = "m32 i586"
TARGET_FPU        = ""
meta
meta-poky
meta-yocto-bsp    = "krogoth:8c69f7d56cbd496aa01ba0738675a170826a536b"
meta-nodejs       = "master:848b0defe8eba6e7ffa97b66e4316c17c92be9d4"
...
brook@vista:~/projects/poky/build$ ./tmp/sysroots/x86_64-linux/usr/bin/qemu-system-i386 -nographic -kernel ./tmp/deploy/images/qemux86/bzImage-qemux86.bin -cpu qemu32 -drive file=./tmp/deploy/images/qemux86/core-image-minimal-qemux86.ext4,if=virtio,format=raw -show-cursor -usb -usbdevice tablet -vga vmware -no-reboot -m 256 -append "vga=0 uvesafb.mode_option=640x480-32 root=/dev/vda rw mem=256M ip=192.168.7.2::192.168.7.1:255.255.255.0 oprofile.timer=1 rootfstype=ext4 "

Poky (Yocto Project Reference Distro) 2.1.1 qemux86 /dev/ttyS0

qemux86 login: root
root@qemux86:~# uname -a
Linux qemux86 4.4.11-yocto-standard #1 SMP PREEMPT Sun Oct 9 19:29:24 CST 2016 i686 GNU/Linux
root@qemux86:~# echo 'console.log("hello world");' > node.js
root@qemux86:~# node node.js
hello world

conf/bblayers.conf修改的內容

BBLAYERS ?= " \
  /home/brook/projects/poky/meta \
  /home/brook/projects/poky/meta-poky \
  /home/brook/projects/poky/meta-yocto-bsp \
  ${TOPDIR}/../meta-nodejs \
  "

conf/local.conf修改的內容

# This sets the default machine to be qemux86 if no other machine is selected:
MACHINE ??= "qemux86"
CORE_IMAGE_EXTRA_INSTALL += "nodejs"

參考資料：
1. meta-nodejs, Node.js的openembedded recipes。
2. JavaScript for IoT: Blinking LED on Raspberry Pi with Node.js , Node.js的demo影片。
3. 「Node.js & IoT: Zero to One」 是一本 Node.js 的入門電子書，內容定位為基礎教學，目標是介紹 Node.js 以及 Node.js + IoT 相關技術主題，每個主題都從基本觀念（Zero）開始，介紹到能撰寫簡單的程式為止（One）。不過目前只有介紹JS的基本語法。
4. Addons。教你如何擴充JS，用C/C++寫一個Node.js module。

Using openembedded to build QEMU

這篇文章主要來說明如何使用Openembedded/Krogoth來build出QEMU for ARM。
步驟大概就是：
先下載yp-krogoth之後，source目錄下的oe-init-build-env，接著再編輯conf/local.conf，最後就是執行bitbake core-image-minimal。
我的Krogoth最後一個commit ID是e93596f。

brook@vista:~/projects$ git clone -b krogoth git://git.yoctoproject.org/poky.git yp-krogoth
Cloning into 'yp-krogoth'...
remote: Counting objects: 339411, done.
remote: Compressing objects: 100% (82247/82247), done.
remote: Total 339411 (delta 251486), reused 338934 (delta 251035)
Receiving objects: 100% (339411/339411), 127.65 MiB | 4.49 MiB/s, done.
Resolving deltas: 100% (251486/251486), done.
Checking connectivity... done.
brook@vista:~/projects$ cd yp-krogoth/
brook@vista:~/projects/yp-krogoth$ git log --oneline -1
e93596f binutils: fix AR issue when opkg is unpacking IPKs containing empty entries
brook@vista:~/projects/yp-krogoth$ . oe-init-build-env
You had no conf/local.conf file. This configuration file has therefore been
created for you with some default values. You may wish to edit it to, for
example, select a different MACHINE (target hardware). See conf/local.conf
for more information as common configuration options are commented.

You had no conf/bblayers.conf file. This configuration file has therefore been
created for you with some default values. To add additional metadata layers
into your configuration please add entries to conf/bblayers.conf.

The Yocto Project has extensive documentation about OE including a reference
manual which can be found at:
    http://yoctoproject.org/documentation

For more information about OpenEmbedded see their website:
    http://www.openembedded.org/


### Shell environment set up for builds. ###

You can now run 'bitbake <target>'

Common targets are:
    core-image-minimal
    core-image-sato
    meta-toolchain
    meta-ide-support

You can also run generated qemu images with a command like 'runqemu qemux86'
brook@vista:~/projects/yp-krogoth/build$ vim conf/local.conf
...內容請看一段
brook@vista:~/projects/yp-krogoth/build$ bitbake core-image-minimal
WARNING: Host distribution "Ubuntu-16.04" has not been validated with this version of the build system; you may possibly experience unexpected failures. It is recommended that you use a tested distribution.
Parsing recipes...done.
Parsing of 871 .bb files complete (0 cached, 871 parsed). 1301 targets, 66 skipped, 0 masked, 0 errors.
NOTE: Resolving any missing task queue dependencies

Build Configuration:
BB_VERSION        = "1.30.0"
BUILD_SYS         = "x86_64-linux"
NATIVELSBSTRING   = "Ubuntu-16.04"
TARGET_SYS        = "arm-poky-linux-gnueabi"
MACHINE           = "qemuarm"
DISTRO            = "poky"
DISTRO_VERSION    = "2.1.1"
TUNE_FEATURES     = "arm armv5 thumb dsp"
TARGET_FPU        = "soft"
meta
meta-poky
meta-yocto-bsp    = "krogoth:e93596fe74927e2e2f4dd7f671994ccb9744cff8"

NOTE: Fetching uninative binary shim from http://downloads.yoctoproject.org/releases/uninative/1.0.1/x86_64-nativesdk-libc.tar.bz2;sha256sum=acf1e44a0ac2e855e81da6426197d36358bf7b4e88e552ef933128498c8910f8
NOTE: Preparing RunQueue
NOTE: Executing SetScene Tasks
...略
brook@vista:~/projects/yp-krogoth/build$ ./tmp/sysroots/x86_64-linux/usr/bin/qemu-system-arm -kernel ./tmp/deploy/images/qemuarm/zImage-qemuarm.bin -M versatilepb -drive file=/home/jpr/projects/yp-krogoth/build/tmp/deploy/images/qemuarm/core-image-minimal-qemuarm.ext4,if=virtio,format=raw -no-reboot -show-cursor -usb -usbdevice tablet -m 128 -nographic -append 'root=/dev/vda rw console=ttyAMA0,115200 console=tty ip=192.168.7.2::192.168.7.1:255.255.255.0 mem=128M highres=off rootfstype=ext4 ' 
audio: Could not init `oss' audio driver
ALSA lib ../../alsa-lib-1.1.0/src/confmisc.c:768:(parse_card) cannot find card '0'
...略
qemuarm login: root
root@qemuarm:~# uname -a
Linux qemuarm 4.4.11-yocto-standard #1 PREEMPT Sun Oct 9 11:36:44 CST 2016 armv5tejl GNU/Linux

conf/local.conf相關修改

change MACHINE for "qemux86" to "qemuarm"
MACHINE ?= "qemuarm"
#MACHINE ?= "qemuarm64"
#MACHINE ?= "qemumips"
#MACHINE ?= "qemumips64"
#MACHINE ?= "qemuppc"
#MACHINE ?= "qemux86"
#MACHINE ?= "qemux86-64"
#
# There are also the following hardware board target machines included for
# demonstration purposes:
#
#MACHINE ?= "beaglebone"
#MACHINE ?= "genericx86"
#MACHINE ?= "genericx86-64"
#MACHINE ?= "mpc8315e-rdb"
#MACHINE ?= "edgerouter"
#
# This sets the default machine to be qemux86 if no other machine is selected:
#MACHINE ??= "qemux86"
...
commout out these 2 lines
#PACKAGECONFIG_append_pn-qemu-native = " sdl"
#PACKAGECONFIG_append_pn-nativesdk-qemu = " sdl"

參考資料：
1. Yocto Project Quick Start
2. Yocto Project Build System/Download

OpenEmbedded - Writing a recipes/package inherit cmake

基本上inherit cmake跟inherit autotools是差不多的，其實cmake class裡面也是有inherit autotool，比較大的差異是，source file在cmake下是放在${PN}目錄下，即package name下，檔案結構如下：

brook@vista:~/oe-core$ tree meta/recipes-support/brook-cmake
meta/recipes-support/brook-cmake
|-- brook-cmake
|   `-- brook-cmake.patch
`-- brook-cmake_1.0.bb
1 directory, 2 files

brook-cmake.patch就是放置CMakeLists.txt、main.c跟LICENSE，其內容如下：

CMakeLists.txt

cmake_minimum_required (VERSION 2.6)
project(brook-cmake-demo)
add_executable(brook-cmake main.c)
install(TARGETS brook-cmake DESTINATION bin)

main.c

#include <stdio.h>

int main(int argc, char *argv[])
{
    printf("hello, cmake\n");
    return 0;
}

brook-cmake_1.0.bb

DESCRIPTION = "Brook CMake Project"
LICENSE = "GPLv2"
LIC_FILES_CHKSUM = "file://LICENSE;md5=5ff2bd2dd80c7cc542a6b8de3ee4ff87"

SRC_URI = "file://brook-cmake.patch \
"

inherit cmake

EXTRA_OEMAKE = "-Wall"

下面這裡是多個版本的寫法

其實寫法都一樣，只是patch file的目錄要包含版本號，檔案結構如下：

brook@vista:~/oe-core/meta/recipes-support$ tree brook-cmake
brook-cmake
|-- brook-cmake-1.0
|   `-- brook-cmake.patch
|-- brook-cmake-2.0
|   `-- brook-cmake.patch
|-- brook-cmake_1.0.bb
`-- brook-cmake_2.0.bb

BB檔與patch的內容跟上面都是一樣的

brook@vista:~/oe-core$ cat meta/recipes-support/brook-cmake/brook-cmake_1.0.bb
DESCRIPTION = "Brook CMake Project"
LICENSE = "GPLv2"
LIC_FILES_CHKSUM = "file://LICENSE;md5=7e4bf6f59b6da8e57ed5425a10a7310b"

SRC_URI = "file://brook-cmake.patch \
"

inherit cmake

BBCLASSEXTEND = "native"

EXTRA_OEMAKE = "-Wall"

brook@vista:~/oe-core$ cat meta/recipes-support/brook-cmake/brook-cmake_2.0.bb
DESCRIPTION = "Brook CMake Project"
LICENSE = "GPLv2"
LIC_FILES_CHKSUM = "file://LICENSE;md5=7e4bf6f59b6da8e57ed5425a10a7310b"

SRC_URI = "file://brook-cmake.patch \
"

inherit cmake

BBCLASSEXTEND = "native"

EXTRA_OEMAKE = "-Wall"

brook@vista:~/oe-core$ cat meta/recipes-support/brook-cmake/brook-cmake-1.0/brook-cmake.patch
From 037c40faba39a11e54f282c3eab5e47a4cf1c7ca Mon Sep 17 00:00:00 2001
From: Brook <rene3210 at gmail.com>
Date: Tue, 27 Sep 2016 20:42:11 +0800
Subject: [PATCH] brook oe demo code

---
 CMakeLists.txt | 5 +++++
 LICENSE        | 1 +
 main.c         | 8 ++++++++
 3 files changed, 14 insertions(+)
 create mode 100644 CMakeLists.txt
 create mode 100644 LICENSE
 create mode 100644 main.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..ee4d6d9
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,5 @@
+cmake_minimum_required (VERSION 2.6)
+project(brook-cmake-demo)
+add_executable(brook-cmake main.c)
+install(TARGETS brook-cmake DESTINATION bin)
+
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..0664320
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1 @@
+"GPLv2"
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..d089aad
--- /dev/null
+++ b/main.c
@@ -0,0 +1,8 @@
+#include 
+
+int main(int argc, char *argv[])
+{
+    printf("hello, cmake 1.0\n");
+    return 0;
+}
+
--
2.7.4

brook@vista:~/oe-core$ cat meta/recipes-support/brook-cmake/brook-cmake-2.0/brook-cmake.patch
From 037c40faba39a11e54f282c3eab5e47a4cf1c7ca Mon Sep 17 00:00:00 2001
From: Brook <rene3210 at gmail.com>
Date: Tue, 27 Sep 2016 20:42:11 +0800
Subject: [PATCH] brook oe demo code

---
 CMakeLists.txt | 5 +++++
 LICENSE        | 1 +
 main.c         | 8 ++++++++
 3 files changed, 14 insertions(+)
 create mode 100644 CMakeLists.txt
 create mode 100644 LICENSE
 create mode 100644 main.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..ee4d6d9
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,5 @@
+cmake_minimum_required (VERSION 2.6)
+project(brook-cmake-demo)
+add_executable(brook-cmake main.c)
+install(TARGETS brook-cmake DESTINATION bin)
+
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..0664320
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1 @@
+"GPLv2"
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..d089aad
--- /dev/null
+++ b/main.c
@@ -0,0 +1,8 @@
+#include 
+
+int main(int argc, char *argv[])
+{
+    printf("hello, cmake 2.0\n");
+    return 0;
+}
+
--
2.7.4

如果沒有特別指定版本的話，會使用最新的，可以透過設定PREFERRED_VERSION_package_name設定特定版本，如

brook@vista:~/oe-core$ grep -H PREFERRED_VERSION build/conf/local.conf
build/conf/local.conf:PREFERRED_VERSION_brook-cmake = "1.0"

相關資訊可以參考Bitbake User Manual/2.3. Preferences and Providers

參考資料：
1. CMake 入門

BitBake User Manual - CH3.3. Sharing Functionality

BitBake 有metadata sharing的機制，基本上分為兩類，include file(.inc)跟class file(.bbclass)，你可以使用include或require來include .inc檔案，其行為就是會將.inc內容插入include那行的位置中。
include跟require相似，差異是，如果檔案不存在include不會error，但是requre就會，如：

include foo_no_exist.inc
require foo_need_exist.inc

你可以使用iherit來使用class file，使用這指令會去尋找對應的class來使用，如：

inherit autotools

如果每個recipes都需要inherit的話，可以在.conf使用INHERIT指令達成這目的，如：

INHERIT += sanity

example：meta/conf/sanity.conf

# Sanity checks for common user misconfigurations
#
# See sanity.bbclass
#
# Expert users can confirm their sanity with "touch conf/sanity.conf"
BB_MIN_VERSION = "1.27.1"

SANITY_ABIFILE = "${TMPDIR}/abi_version"

SANITY_VERSION ?= "1"
LOCALCONF_VERSION  ?= "1"
LAYER_CONF_VERSION ?= "6"
SITE_CONF_VERSION  ?= "1"

INHERIT += "sanity"

example：meta/classes/sanity.bbclass

參考資料：
1. BitBake User Manual

OpenEmbedded -- Creating and using an SDK

SDK包含了開發時所需的相關檔案，有些還包含了整個開發環境(tool/command)，避免系統的tool/command跟SDK需要的不同造成的error，一個SDK應該包含以下內容：(YOCTO Slides)

1. Compilers or cross-compilers
2. Linkers
3. Library headers
4. Debuggers
5. Custom utilities

這篇文章就是在介紹如何使用Openembedded建立一個generic SDK供他人開發application，使用指令bitbake -v meta-toolchain即可產生generic SDK，並產生一個install的script，放置於oe/oe-core/build/tmp-eglibc/deploy/sdk/底下，執行過程如下

brook@vista:/home/brook/oe/oe-core/build$ bitbake -v meta-toolchain

...

+ chmod +x /home/brook/oe/oe-core/build/tmp-eglibc/deploy/sdk/oecore-x86_64-armv7a-vfp-neon-toolchain-oe-core.0.sh

+ cat /home/brook/oe/oe-core/build/tmp-eglibc/deploy/sdk/oecore-x86_64-armv7a-vfp-neon-toolchain-oe-core.0.tar.bz2

+ rm /home/brook/oe/oe-core/build/tmp-eglibc/deploy/sdk/oecore-x86_64-armv7a-vfp-neon-toolchain-oe-core.0.tar.bz2


NOTE: Tasks Summary: Attempted 1685 tasks of which 1312 didn't need to be rerun and all succeeded.
brook@vista:/home/brook/oe/oe-core/build$ tree tmp-eglibc/deploy/sdk/
tmp-eglibc/deploy/sdk/
`-- oecore-x86_64-armv7a-vfp-neon-toolchain-oe-core.0.sh

0 directories, 1 file

接著直要將底下的script(oecore-x86_64-armv7a-vfp-neon-toolchain-oe-core.0.sh)給developer開發即可，-d後面帶安裝目錄，安裝過程需要SUDO權限，

brook@vista:/home/brook/oe/oe-core/build$ ./tmp-eglibc/deploy/sdk/oecore-x86_64-armv7a-vfp-neon-toolchain-oe-core.0.sh --help
Usage: oecore-x86_64-armv7a-vfp-neon-toolchain-oe-core.0.sh [-y] [-d <dir>]
  -y         Automatic yes to all prompts
  -d <dir>   Install the SDK to <dir>
======== Advanced DEBUGGING ONLY OPTIONS ========
  -S         Save relocation scripts
  -R         Do not relocate executables
  -D         use set -x to see what is going on
brook@vista:~$ /home/brook/oe/oe-core/build/tmp-eglibc/deploy/sdk/oecore-x86_64-armv7a-vfp-neon-toolchain-oe-core.0.sh -d /opt/oe -D
+ printf 'Enter target directory for SDK (default: /usr/local/oecore-x86_64): '
Enter target directory for SDK (default: /usr/local/oecore-x86_64): + '[' /opt/oe = '' ']'
+ echo /opt/oe
/opt/oe

...

+ '[' 0 = 0 ']'
+ /usr/bin/sudo rm /SSD/opt/oe/relocate_sdk.py /SSD/opt/oe/relocate_sdk.sh
+ echo 'SDK has been successfully set up and is ready to be used.'
SDK has been successfully set up and is ready to be used.
+ exit 0

要使用SDK之前，必須先source安裝目錄下開頭為environment-setup-的script，設置相關的環境變數，我的script內容如下

export PATH=/SSD/opt/oe/sysroots/x86_64-oesdk-linux/usr/bin:/SSD/opt/oe/sysroots/x86_64-oesdk-linux/usr/bin/armv
7a-vfp-neon-oe-linux-gnueabi:$PATH
export PKG_CONFIG_SYSROOT_DIR=/SSD/opt/oe/sysroots/armv7a-vfp-neon-oe-linux-gnueabi
export PKG_CONFIG_PATH=/SSD/opt/oe/sysroots/armv7a-vfp-neon-oe-linux-gnueabi/usr/lib/pkgconfig
export CONFIG_SITE=/SSD/opt/oe/site-config-armv7a-vfp-neon-oe-linux-gnueabi
export CC="arm-oe-linux-gnueabi-gcc  -march=armv7-a -mthumb-interwork -mfloat-abi=softfp -mfpu=neon -mthumb-inte
rwork --sysroot=/SSD/opt/oe/sysroots/armv7a-vfp-neon-oe-linux-gnueabi"
export CXX="arm-oe-linux-gnueabi-g++  -march=armv7-a -mthumb-interwork -mfloat-abi=softfp -mfpu=neon -mthumb-int
erwork --sysroot=/SSD/opt/oe/sysroots/armv7a-vfp-neon-oe-linux-gnueabi"
export CPP="arm-oe-linux-gnueabi-gcc -E  -march=armv7-a -mthumb-interwork -mfloat-abi=softfp -mfpu=neon -mthumb-interwork --sysroot=/SSD/opt/oe/sysroots/armv7a-vfp-neon-oe-linux-gnueabi"
export AS="arm-oe-linux-gnueabi-as "
export LD="arm-oe-linux-gnueabi-ld  --sysroot=/SSD/opt/oe/sysroots/armv7a-vfp-neon-oe-linux-gnueabi"
export GDB=arm-oe-linux-gnueabi-gdb
export STRIP=arm-oe-linux-gnueabi-strip
export RANLIB=arm-oe-linux-gnueabi-ranlib
export OBJCOPY=arm-oe-linux-gnueabi-objcopy
export OBJDUMP=arm-oe-linux-gnueabi-objdump
export AR=arm-oe-linux-gnueabi-ar
export NM=arm-oe-linux-gnueabi-nm
export M4=m4
export TARGET_PREFIX=arm-oe-linux-gnueabi-
export CONFIGURE_FLAGS="--target=arm-oe-linux-gnueabi --host=arm-oe-linux-gnueabi --build=x86_64-linux --with-libtool-sysroot=/SSD/opt/oe/sysroots/armv7a-vfp-neon-oe-linux-gnueabi"
export CFLAGS=" -O2 -fexpensive-optimizations -frename-registers -fomit-frame-pointer"
export CXXFLAGS=" -O2 -fexpensive-optimizations -frename-registers -fomit-frame-pointer -fpermissive"
export LDFLAGS="-Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed"
export CPPFLAGS=""
export OECORE_NATIVE_SYSROOT="/SSD/opt/oe/sysroots/x86_64-oesdk-linux"
export OECORE_TARGET_SYSROOT="/SSD/opt/oe/sysroots/armv7a-vfp-neon-oe-linux-gnueabi"
export OECORE_ACLOCAL_OPTS="-I /SSD/opt/oe/sysroots/x86_64-oesdk-linux/usr/share/aclocal"
export OECORE_DISTRO_VERSION="20151225"
export OECORE_SDK_VERSION="oe-core.0"
export PYTHONHOME=/SSD/opt/oe/sysroots/x86_64-oesdk-linux/usr
export ARCH=arm
export CROSS_COMPILE=arm-oe-linux-gnueabi-

以下是我用這SDK編譯一個檔案，並放入target中執行

brook@vista:~$ source /opt/oe/environment-setup-armv7a-vfp-neon-oe-linux-gnueabi
brook@vista:~$ cat main.c
#include <stdio.h>

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

brook@vista:~$ $CC -o brook-sdk main.c

D:\Projects>adb push z:\brook-sdk /
688 KB/s (5644 bytes in 0.008s)

D:\Projects>adb shell chmod +x /brook-sdk

D:\Projects>adb shell /brook-sdk
hello

開發環境架構圖

參考資料：
1. Yocto Project and OpenEmbedded development course
2. Yocto Project Quick Start -- SDK Generation

OpenEmbedded - Writing Meta Data for adding Kernel Module package

繼OpenEmbedded User Manual - CH3, Writing Meta Data (Adding packages)之後，這一篇是教導如何新增Kernel Module package。 BB檔的寫法與OpenEmbedded User Manual - CH3, Writing Meta Data (Adding packages)雷同，只是我們這次iherit的class是module

/oe-core/meta/recipes-kernel/brook/brook_1.0.bb

inherit module
DESCRIPTION = "Brook Out Tree Kernel Module"
LICENSE = "GPLv2"
LIC_FILES_CHKSUM = "file://LICENSE;md5=5ff2bd2dd80c7cc542a6b8de3ee4ff87"

PR = "r1-${KERNEL_VERSION}"

# This DEPENDS is to serialize kernel module builds
DEPENDS = "virtual/kernel"


SRC_URI = "file://brook.patch \
"

S = "${WORKDIR}/brook-linux-${PV}"

這邊的SRC_URI我是使用patch格式，當然你也可以使用zip格式，但是zip格式需要考慮目錄名稱必須為"${WORKDIR}/brook-linux-${PV}"，即bb檔中的S，但是如果是patch就不用管S目錄名稱為何了。

完整檔案結構如下

後面會陸續介紹每個檔案

    /oe-core/meta/recipes-kernel/brook
    |-- brook_1.0.bb
    |-- files
    |   `-- brook.patch
    `-- git
        |-- LICENSE
        |-- Makefile
        `-- main.c

Makefile

ifneq ($(KERNELRELEASE),)
# obj-m := <module_name>.o
# <module_name>-y := <src1>.o <src2>.o ...

        EXTRA_CFLAGS += -DYAFFS_OUT_OF_TREE

        obj-m := brook.o

        brook-objs := main.o
else
        PWD := $(shell pwd)

modules:
 $(MAKE) -C $(KERNEL_SRC) M=$(PWD) modules

modules_install:
 $(MAKE) -C $(KERNEL_SRC) M=$(PWD) modules_install

clean:
 $(MAKE) -C $(KERNEL_SRC) M=$(PWD) clean
endif

這是一般的Kernel Module寫法，沒有特別的地方，Out Tree build時KERNELRELEASE為空字串，所以會用下面那段。

License的內容就只有"License: GPL"這個字串

main.c

Module的主程式，只是在init與exit時印出簡單字串而已。

#include <linux/module.h>

MODULE_AUTHOR("Brook");
MODULE_DESCRIPTION("Kernel module for demo");
MODULE_LICENSE("GPL");

static int __init brook_init(void)
{
        printk(KERN_INFO "Brook Module Init\n");
        return 0;
}
module_init(brook_init);

static void __exit brook_exit(void)
{
        printk(KERN_INFO "Brook Module Exit\n");
        return;
}
module_exit(brook_exit);

brook.patch

這是我把檔案全部放在git目錄底下，做source control，並用git format-patch產生的，將產生後的檔案放置files/brook.patch。

OpenEmbedded User Manual - CH3, Writing Meta Data (Adding packages)

如同User manual提的，讓我們從寫package的description跟license開始，我們寫一個brook_1.0.bb開始

description

DESCRIPTION = "Brook's first application"
HOMEPAGE = "http://www.brook.com/oe/"
LICENSE = "Brook-Proprietary"

基本上這些參數都只是描述，也就是字串，至於LICENSE有公用哪些選項，請參考Recipe License Fields。

define dependency

DEPENDS = "gtk+"
RDEPENDS = "cool-ttf-fonts"

DEPENDS是build時需要哪個package，RDEPENDS則是執行時需要哪個package，也就是說如果該brook_1.0被加到image，則RDEPENDS所列的也都會被加到image之中。

source location

SRC_URI = "http://127.0.0.1/brook/${P}.tar.bz2"
SRC_URI[md5sum] = "6abf52e3f874f67bc4663d0986493970"
SRC_URI[sha256sum] = "7aa5130f9648f0948ebaad270a4fe1112e4cc06895580dab85da26baa37fd4f6"

SRC_URI是指定檔案所在的位置，可以支援http、ftp、git、svn、file等，詳情可參考SRC_URI variable，SRC_URI[md5sum]與SRC_URI[sha256sum]是去驗證檔案是否正確，可以透過md5sum file_name與sha256sum file_name算出。當中的${P}=${PN}-${PV}，${PN}是Package Name，${PV}是Package Version。

build system selection

在開始真正build package之前，我們必須決定這個package使用哪個build system，如果這個package需要先執行configure script然後在make，那麼通常就會選用autotools，更多關於autotools class，其他inherit之後再來討論。

到此可以真正開始build brook這個package了，bitbake brook。

完整brook_1.0.bb

DESCRIPTION = "Brook's first application"
HOMEPAGE = "http://www.brook.com/oe/"
LICENSE = "Brook-Proprietary"
LIC_FILES_CHKSUM = "file://COPYING;md5=dcb2a5c2b6d6fea1a0835c08d71ad817"

SRC_URI = "http://127.0.0.1/brook/${P}.tar.bz2"
SRC_URI[md5sum] = "6abf52e3f874f67bc4663d0986493970"
SRC_URI[sha256sum] = "7aa5130f9648f0948ebaad270a4fe1112e4cc06895580dab85da26baa37fd4f6"
inherit autotools

Example of Source Code

brook-1.0/Makefile

all: brook

brook: main.o
 ${CC} $? -o $@
install:
 install -d -m 755 ${DESTDIR}/bin
 install -m 755 brook ${DESTDIR}/bin

brook-1.0/main.c

#include <stdio.h>

int main(int argc, char *argv[])
{
    printf("Hello world, Brook\n");
    return 0;
}

參考資料：
1. OpenEmbedded User Manual
2. OpenEmbedded - Style Guide
3. OpenEmbedded - Recipe License Fields

LIC_FILES_CHKSUM does not match

如果出現以下錯誤

ERROR: brook: Recipe file does not have license file information (LIC_FILES_CHKSUM)
ERROR: Licensing Error: LIC_FILES_CHKSUM does not match, please fix

可以在bb file中加入

LIC_FILES_CHKSUM = "file://COPYING;md5=dcb2a5c2b6d6fea1a0835c08d71ad817"

其中COPYING就是LICENSE檔案位置，我是指到source file解開後的COPYING檔案位置與其對應的md5sum。