作為一個linux小白，內核知識也不太懂，但實驗室需要為了提高代碼實時性，一路下來邊踩坑邊GOOGLE，現在對前一段經歷進行總結。
平台：
硬件：Intel NUC8i7BEH
軟件：基於ubuntu16.04 LTS（18.04近期准備測試…）
一、前期操作
安裝主要參考鏈接如下：
1、(Beta) Xenomai 3.0.5 on Ubuntu 14.04/16.04/
2、GitLab_XENOMAI官方網址
3、這個老哥的紀錄（有一次跟着官網沒成功，跟着這個成功了…簡直妙啊）
正常跟着提示安裝即可，一定要確保每一步沒有奇怪的報錯，有的話肯定自己哪里沒弄好，趁早停止下來找原因…接下來對幾處關鍵地方進行記錄：
1、configure the linux kernel部分：
Recommended options:
* General setup
--> Local version - append to kernel release: -xenomai-3.0.5 #一定要與自己的xenomai版本對應
--> Timers subsystem
--> High Resolution Timer Support (Enable)
* Xenomai/cobalt
--> Sizes and static limits
--> Number of registry slots (512 --> 4096)
--> Size of system heap (Kb) (512 --> 4096)
--> Size of private heap (Kb) (64 --> 256)
--> Size of shared heap (Kb) (64 --> 256)
--> Maximum number of POSIX timers per process (128 --> 512)
--> Drivers
--> RTnet
--> RTnet, TCP/IP socket interface (Enable)
--> Drivers
--> New intel(R) PRO/1000 PCIe (Enable)
--> Realtek 8169 (Enable)
--> Loopback (Enable)
--> Add-Ons
--> Real-Time Capturing Support (Enable)
* Power management and ACPI options
--> CPU Frequency scaling
--> CPU Frequency scaling (Disable)
--> ACPI (Advanced Configuration and Power Interface) Support
--> Processor (Disable)
--> CPU Idle
--> CPU idle PM support (Disable)
* Pocessor type and features
--> Enable maximum number of SMP processors and NUMA nodes (Disable)
// Ref : http://xenomai.org/pipermail/xenomai/2017-September/037718.html
--> Processor family
**#執行“cat /proc/cpuinfo | grep family”確定自己應該選Generic-***還是選Core 2/newer** **Xeon**
--> Core 2/newer Xeon (if "cat /proc/cpuinfo | grep family" returns 6, set as Generic otherwise)
// Xenomai will issue a warning about CONFIG_MIGRATION, disable those in this order
--> Transparent Hugepage Support (Disable)
--> Allow for memory compaction (Disable)
--> Contiguous Memory Allocation (Disable)
--> Allow for memory compaction
--> Page Migration (Disable)
* Device Drivers
--> Staging drivers
--> Unisys SPAR driver support
--> Unisys visorbus driver (Disable)
2、電腦比較渣，后面構建編譯過程比較費時間，奧利給！
3、Configure GRUB and reboot：自己配置后的grub文件如下，
一定要根據自己的CPU和GPU配置好其中的“GRUB_CMDLINE_LINUX_DEFAULT=*”。
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'
#GRUB_DEFAULT=0
#GRUB_HIDDEN_TIMEOUT=0
#GRUB_HIDDEN_TIMEOUT_QUIET=true
#GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
#GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
#GRUB_CMDLINE_LINUX="locale=en_US"
GRUB_DEFAULT="Advanced options for Ubuntu>Ubuntu, with Linux 4.9.38-xenomai-3.0.9"
#GRUB_DEFAULT=saved
#GRUB_SAVEDEFAULT=true
# Comment the following lines
#GRUB_HIDDEN_TIMEOUT=0
#GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=5
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.enable_rc6=0 i915.enable_dc=0 noapic xenomai.allowed_group=1234"
GRUB_CMDLINE_LINUX=""
4、跟着文檔一路下來，最后就能愉快的測試安裝咯：希望大家都能正常得到以下提示！
== Sampling period: 100 us
== Test mode: periodic user-mode task
== All results in microseconds
warming up...
RTT| 00:00:01 (periodic user-mode task, 100 us period, priority 99)
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst
RTD| 0.174| 0.464| 1.780| 0| 0| 0.174| 1.780
RTD| 0.088| 0.464| 1.357| 0| 0| 0.088| 1.780
RTD| 0.336| 0.464| 1.822| 0| 0| 0.088| 1.822
RTD| 0.342| 0.464| 1.360| 0| 0| 0.088| 1.822
RTD| 0.327| 0.462| 2.297| 0| 0| 0.088| 2.297
RTD| 0.347| 0.463| 1.313| 0| 0| 0.088| 2.297
RTD| 0.314| 0.464| 1.465| 0| 0| 0.088| 2.297
RTD| 0.190| 0.464| 1.311| 0| 0| 0.088| 2.297
二、BUG記錄（希望有懂的大佬多多賜教）
1、前期使用xenomai3.0.5+linux4.9.38版本編譯安裝，雖然能成功，但隨后用的時候總是會突然死機，鍵盤鼠標全都不能用…有時甚至有線無線網都不能正常連接，只能靠無線網卡苟着…
2、有次在運行xeno latency測試安裝時候，出現如下報錯：
vision@vision:~/xenomai-3.0.5/xenomai-3$ xeno latency
0"000.000| BUG in low_init(): [main] ABI mismatch: required r17, provided r16
官網這里有類似記錄，可惜我當時沒看懂，大概是說我辛辛苦苦配的linux內核版本過低，有沖突？？
解決辦法：故隨后換用了xenomai3.0.9+linux4.9.90重新裝了一次，這次竟然成功了…很迷…
3、OROCOS RTT on Xenomai：
配置RTT ROS Integration 2.9 on Xenomai期間，執行以下命令時候會卸載之前裝好的ROS…真坑，畢竟貧困山區的孩子裝一次ROS不容易啊！一定要慎重！
rosdep install --from-paths ~/isir/rtt_ros-2.9_ws/src --ignore-src --rosdistro kinetic -y -r
4、終端terminal打不開
試圖根據官網這里配置ROS Kinetic ++，執行以下命令並重啟以后，紅紅的終端突然就沒了…慎重啊兄弟們！
sudo locale-gen en_US #warnings might occur
sudo locale-gen en_US.UTF-8
sudo nano /etc/environment
# put theses lines
LANGUAGE=en_US
LC_ALL=en_US
# Reboot !
解決辦法：/etc/environment文件中原來是啥就是啥，不懂的話不要輕易加東西（大佬除外…），去掉自己加入的兩行語言配置就好了~
5、將實時性要求高的代碼放入xenomai的實時進程
期間經常會遇到檢索不到某個頭文件，一般是路徑的問題，沒有正確include進來，可以到**/usr/xenomai/include/** 下多看看，xenomai的東西基本都在這里。
若遇到報錯error: invalid use of incomplete type ‘const struct timespec’，我當時是把包含這個結構體定義的頭文件include進入所需要用到的.cpp文件內即可解決～
6、socket：address family not supported by protocol
這個問題是在測試實時進程和普通進程間的通信時遇到的，參考的官網這里，直接找到路徑/usr/xenomai/demo下的可執行文件xddp-label，淦！錯誤提示如下：
vision@vision:/usr/xenomai/demo$ sudo ./xddp-label
socket：address family not supported by protocol
解決辦法：
回到官網這里的內核配置部分，重新進行以下內核選項配置：
vision@vision:$ cd linux-4.9.38
vision@vision:/linux-4.9.38$ make menuconfig
----------------------------------------------------------------------------
# 更改以下地方配置
* Xenomai/cobalt (NEW) --->
Drivers --->
Real-time IPC drivers --->
<*> RTIPC protocol family
[*] XDDP cross-domain datagram protocol (NEW)
[*] IDDP intra-domain datagram protocol (NEW)
(32) Number of IDDP communication ports (NEW)
[*] Buffer protocol (NEW)
(32) Number of BUFP communication ports (NEW)
-----------------------------------------------------------------------------
# save the new configuration
vision@vision:/linux-4.9.38$ sudo make -j12 && sudo make -j12 modules && sudo make -j12 modules_install && sudo make -j12 install
之后重啟系統，在開機時的內核切換界面會看到兩個xenomai內核：linux-4.9.90-xenomai-3.0.9（修改后的）和linux-4.9.90-xenomai-3.0.9.old（原先的），選擇新生成的內核（linux-4.9.90-xenomai-3.0.9）進入系統即可。
此時，在運行即可出現以下界面，顯示實時進程與普通進程之間通信成功：
vision@vision:/usr/xenomai/demo$ sudo ./xddp-label
realtime_thread2: NRT peer is reading from /dev/rtp0
realtime_thread2: sent 22 bytes, "Surfing With The Alien"
realtime_thread1: "Surfing With The Alien" relayed by peer
realtime_thread2: sent 14 bytes, "Lords of Karma"
realtime_thread1: "Lords of Karma" relayed by peer
realtime_thread2: sent 12 bytes, "Banana Mango"
realtime_thread1: "Banana Mango" relayed by peer
realtime_thread2: sent 13 bytes, "Psycho Monkey"
realtime_thread1: "Psycho Monkey" relayed by peer
realtime_thread2: sent 21 bytes, "Luminous Flesh Giants"
realtime_thread1: "Luminous Flesh Giants" relayed by peer
realtime_thread2: sent 15 bytes, "Moroccan Sunset"
realtime_thread1: "Moroccan Sunset" relayed by peer
realtime_thread2: sent 12 bytes, "Satch Boogie"
realtime_thread1: "Satch Boogie" relayed by peer
realtime_thread2: sent 22 bytes, "Flying In A Blue Dream"
realtime_thread1: "Flying In A Blue Dream" relayed by peer
realtime_thread2: sent 4 bytes, "Ride"
realtime_thread1: "Ride" relayed by peer
realtime_thread2: sent 11 bytes, "Summer Song"
realtime_thread1: "Summer Song" relayed by peer
但終止一次sudo ./xddp-label命令，再次運行時，會出現以下問題，附解決辦法：
vision@vision:/usr/xenomai/demo$ sudo ./xddp-label
[sudo] password for vision:
bind: File exists
--------------------------------------------------------
# 解決方式：
vision@vision:/usr/xenomai/bin$ ps -A | grep xddp
2858 ? 00:00:00 xddp-label
vision@vision:/usr/xenomai/bin$ sudo kill -9 2858
---------------------------------------------------------
# 再次運行即可正常通信
vision@vision:/usr/xenomai/demo$ sudo ./xddp-label
realtime_thread2: NRT peer is reading from /dev/rtp0
realtime_thread2: sent 22 bytes, "Surfing With The Alien"
realtime_thread1: "Surfing With The Alien" relayed by peer
7、error while loading shared libraries: libcobalt.so.2: cannot open shared object file: No such file or directory。
這個問題出現在以下情景：自己嘗試通過編寫cmakelists.txt和xddp.cpp源文件，然后通過cmake方式進行編譯之，從而測試xenomai實時進程和Linux普通進程間的通信情況。
最終發現是由於在cmakelists.txt文件中缺少了libcobalt.so.2動態庫文件的引入而導致的，更改后的代碼：
（1）xddp.cpp：
/* * Copyright (C) 2009 Philippe Gerum <rpm@xenomai.org>. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. * * * XDDP-based RT/NRT threads communication demo. * * Real-time Xenomai threads and regular Linux threads may want to * exchange data in a way that does not require the former to leave * the real-time domain (i.e. secondary mode). Message pipes - as * implemented by the RTDM-based XDDP protocol - are provided for this * purpose. * * On the Linux domain side, pseudo-device files named /dev/rtp<minor> * give regular POSIX threads access to non real-time communication * endpoints, via the standard character-based I/O interface. On the * Xenomai domain side, sockets may be bound to XDDP ports, which act * as proxies to send and receive data to/from the associated * pseudo-device files. Ports and pseudo-device minor numbers are * paired, meaning that e.g. port 7 will proxy the traffic for * /dev/rtp7. Therefore, port numbers may range from 0 to * CONFIG_XENO_OPT_PIPE_NRDEV - 1. * * All data sent through a bound/connected XDDP socket via sendto(2) or * write(2) will be passed to the peer endpoint in the Linux domain, * and made available for reading via the standard read(2) system * call. Conversely, all data sent using write(2) through the non * real-time endpoint will be conveyed to the real-time socket * endpoint, and made available to the recvfrom(2) or read(2) system * calls. * * ASCII labels can be attached to bound ports, in order to connect * sockets to them in a more descriptive way than using plain numeric * port values. * * The example code below illustrates the following process: * * realtime_thread1----------------------------->----------+ * => get socket | * => bind socket to port "xddp-demo | * => read traffic from NRT domain via recvfrom() <--+--+ * | | * realtime_thread2----------------------------------------+ | * => get socket | | * => connect socket to port "xddp-demo" | | * => write traffic to NRT domain via sendto() v | * | ^ * regular_thread------------------------------------------+ | * => open /proc/xenomai/registry/rtipc/xddp/xddp-demo | | * => read traffic from RT domain via read() | | * => mirror traffic to RT domain via write() +--+ */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <malloc.h>
#include <pthread.h>
#include <fcntl.h>
#include <errno.h>
#include </usr/xenomai/include/rtdm/ipc.h>
pthread_t rt1, rt2, nrt;
#define XDDP_PORT_LABEL "xddp-demo"
static const char *msg[] = {
"Surfing With The Alien",
"Lords of Karma",
"Banana Mango",
"Psycho Monkey",
"Luminous Flesh Giants",
"Moroccan Sunset",
"Satch Boogie",
"Flying In A Blue Dream",
"Ride",
"Summer Song",
"Speed Of Light",
"Crystal Planet",
"Raspberry Jam Delta-V",
"Champagne?",
"Clouds Race Across The Sky",
"Engines Of Creation"
};
static void fail(const char *reason)
{
perror(reason);
exit(EXIT_FAILURE);
}
static void *realtime_thread1(void *arg)
{
struct rtipc_port_label plabel;
struct sockaddr_ipc saddr;
char buf[128];
int ret, s;
/* * Get a datagram socket to bind to the RT endpoint. Each * endpoint is represented by a port number within the XDDP * protocol namespace. */
s = socket(AF_RTIPC, SOCK_DGRAM, IPCPROTO_XDDP);
if (s < 0) {
perror("socket");
exit(EXIT_FAILURE);
}
/* * Set a port label. This name will be registered when * binding, in addition to the port number (if given). */
strcpy(plabel.label, XDDP_PORT_LABEL);
ret = setsockopt(s, SOL_XDDP, XDDP_LABEL,
&plabel, sizeof(plabel));
if (ret)
fail("setsockopt");
/* * Bind the socket to the port, to setup a proxy to channel * traffic to/from the Linux domain. Assign that port a label, * so that peers may use a descriptive information to locate * it. For instance, the pseudo-device matching our RT * endpoint will appear as * /proc/xenomai/registry/rtipc/xddp/<XDDP_PORT_LABEL> in the * Linux domain, once the socket is bound. * * saddr.sipc_port specifies the port number to use. If -1 is * passed, the XDDP driver will auto-select an idle port. */
memset(&saddr, 0, sizeof(saddr));
saddr.sipc_family = AF_RTIPC;
saddr.sipc_port = -1;
ret = bind(s, (struct sockaddr *)&saddr, sizeof(saddr));
if (ret)
fail("bind");
for (;;) {
/* Get packets relayed by the regular thread */
ret = recvfrom(s, buf, sizeof(buf), 0, NULL, 0);
if (ret <= 0)
fail("recvfrom");
printf("%s: \"%.*s\" relayed by peer\n", __FUNCTION__, ret, buf);
}
return NULL;
}
static void *realtime_thread2(void *arg)
{
struct rtipc_port_label plabel;
struct sockaddr_ipc saddr;
int ret, s, n = 0, len;
struct timespec ts;
struct timeval tv;
socklen_t addrlen;
s = socket(AF_RTIPC, SOCK_DGRAM, IPCPROTO_XDDP);
if (s < 0) {
perror("socket");
exit(EXIT_FAILURE);
}
/* * Set the socket timeout; it will apply when attempting to * connect to a labeled port, and to recvfrom() calls. The * following setup tells the XDDP driver to wait for at most * one second until a socket is bound to a port using the same * label, or return with a timeout error. */
tv.tv_sec = 1;
tv.tv_usec = 0;
ret = setsockopt(s, SOL_SOCKET, SO_RCVTIMEO,
&tv, sizeof(tv));
if (ret)
fail("setsockopt");
/* * Set a port label. This name will be used to find the peer * when connecting, instead of the port number. */
strcpy(plabel.label, XDDP_PORT_LABEL);
ret = setsockopt(s, SOL_XDDP, XDDP_LABEL,
&plabel, sizeof(plabel));
if (ret)
fail("setsockopt");
memset(&saddr, 0, sizeof(saddr));
saddr.sipc_family = AF_RTIPC;
saddr.sipc_port = -1; /* Tell XDDP to search by label. */
ret = connect(s, (struct sockaddr *)&saddr, sizeof(saddr));
if (ret)
fail("connect");
/* * We succeeded in making the port our default destination * address by using its label, but we don't know its actual * port number yet. Use getpeername() to retrieve it. */
addrlen = sizeof(saddr);
ret = getpeername(s, (struct sockaddr *)&saddr, &addrlen);
if (ret || addrlen != sizeof(saddr))
fail("getpeername");
printf("%s: NRT peer is reading from /dev/rtp%d\n",
__FUNCTION__, saddr.sipc_port);
for (;;) {
len = strlen(msg[n]);
/* * Send a datagram to the NRT endpoint via the proxy. * We may pass a NULL destination address, since the * socket was successfully assigned the proper default * address via connect(2). */
ret = sendto(s, msg[n], len, 0, NULL, 0);
if (ret != len)
fail("sendto");
printf("%s: sent %d bytes, \"%.*s\"\n",
__FUNCTION__, ret, ret, msg[n]);
n = (n + 1) % (sizeof(msg) / sizeof(msg[0]));
/* * We run in full real-time mode (i.e. primary mode), * so we have to let the system breathe between two * iterations. */
ts.tv_sec = 0;
ts.tv_nsec = 500000000; /* 500 ms */
clock_nanosleep(CLOCK_REALTIME, 0, &ts, NULL);
}
return NULL;
}
static void *regular_thread(void *arg)
{
char buf[128], *devname;
int fd, ret;
if (asprintf(&devname,
"/proc/xenomai/registry/rtipc/xddp/%s",
XDDP_PORT_LABEL) < 0)
fail("asprintf");
fd = open(devname, O_RDWR);
free(devname);
if (fd < 0)
fail("open");
for (;;) {
/* Get the next message from realtime_thread2. */
ret = read(fd, buf, sizeof(buf));
if (ret <= 0)
fail("read");
/* Relay the message to realtime_thread1. */
ret = write(fd, buf, ret);
if (ret <= 0)
fail("write");
}
return NULL;
}
int main(int argc, char **argv)
{
struct sched_param rtparam = { .sched_priority = 42 };
pthread_attr_t rtattr, regattr;
sigset_t set;
int sig;
sigemptyset(&set);
sigaddset(&set, SIGINT);
sigaddset(&set, SIGTERM);
sigaddset(&set, SIGHUP);
pthread_sigmask(SIG_BLOCK, &set, NULL);
pthread_attr_init(&rtattr);
pthread_attr_setdetachstate(&rtattr, PTHREAD_CREATE_JOINABLE);
pthread_attr_setinheritsched(&rtattr, PTHREAD_EXPLICIT_SCHED);
pthread_attr_setschedpolicy(&rtattr, SCHED_FIFO);
pthread_attr_setschedparam(&rtattr, &rtparam);
/* Both real-time threads have the same attribute set. */
errno = pthread_create(&rt1, &rtattr, &realtime_thread1, NULL);
if (errno)
fail("pthread_create");
errno = pthread_create(&rt2, &rtattr, &realtime_thread2, NULL);
if (errno)
fail("pthread_create");
pthread_attr_init(®attr);
pthread_attr_setdetachstate(®attr, PTHREAD_CREATE_JOINABLE);
pthread_attr_setinheritsched(®attr, PTHREAD_EXPLICIT_SCHED);
pthread_attr_setschedpolicy(®attr, SCHED_OTHER);
errno = pthread_create(&nrt, ®attr, ®ular_thread, NULL);
if (errno)
fail("pthread_create");
sigwait(&set, &sig);
pthread_cancel(rt1);
pthread_cancel(rt2);
pthread_cancel(nrt);
pthread_join(rt1, NULL);
pthread_join(rt2, NULL);
pthread_join(nrt, NULL);
return 0;
}
（2）CMakeLists.txt：
cmake_minimum_required(VERSION 3.7.2)
project(xddp)
#file(GLOB SOURCES "/usr/xenomai/include/alchemy/*.*")
# set(CMAKE_CXX_STANDARD 11)
#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
add_compile_options(-std=c++11)
include_directories(/usr/xenomai/include/alchemy/)
include_directories(/usr/xenomai/include/)
include_directories(/usr/xenomai/include/rtdm)
include_directories(/usr/xenomai/cobalt/)
include_directories(/usr/xenomai/posix/)
include_directories(/usr/xenomai/boilerplate/)
link_directories(/usr/xenomai/lib)
set(xeno_cflags_params "--skin=posix" "--cflags")
execute_process(
COMMAND xeno-config ${xeno_cflags_params}
OUTPUT_VARIABLE xeno_cflags
OUTPUT_STRIP_TRAILING_WHITESPACE)
set(xeno_ldflags_params "--skin=posix" "--ldflags")
execute_process(
COMMAND xeno-config ${xeno_ldflags_params}
OUTPUT_VARIABLE xeno_ldflags
OUTPUT_STRIP_TRAILING_WHITESPACE)
# Compiler and linker options
set(CMAKE_C_FLAGS "${CMAKE_CXX_FLAGS} ${xeno_cflags}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${xeno_cflags}")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${xeno_ldflags}")
set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${xeno_ldflags}")
add_executable(xddp xddp.cpp )
target_link_libraries(xddp ${XENO_NATIVE_LDFLAGS} /usr/xenomai/bin)
#target_link_libraries(xddp ${LIB_DIR}/libalchemy.so ${LIB_DIR}/libanalogy.so
# ${LIB_DIR}/libcobalt.so ${LIB_DIR}/libmodechk.so ${LIB_DIR}/libcopperplate.so
# ${LIB_DIR}/libnative.so ${LIB_DIR}/libpsos.so ${LIB_DIR}/libpthread_rt.so
# ${LIB_DIR}/librtdm.so ${LIB_DIR}/libsmokey.so ${LIB_DIR}/libtrank.so
# ${LIB_DIR}/libuitron.so ${LIB_DIR}/libvrtx.so ${LIB_DIR}/libvxworks.so ${LIB_DIR}/libxenomai.so)
#