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yangzhenghan committed Feb 28, 2024
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168 changes: 158 additions & 10 deletions content/posts/龙芯开发板移植IgH EtherCAT Master.md
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
---
title: "龙芯开发板移植 IgH EtherCAT Master"
date: 2024-02-23T12:54:31+08:00
lastmod: 2024-02-28T13:05:54+08:00
lastmod: 2024-02-28T18:56:32+08:00
draft: false
description: 龙芯2K0500开发板移植EtherCAT主站程序和EPICS EtherCAT模块
tags: ["linux", "EPICS", "龙芯"]
Expand Down Expand Up @@ -386,7 +386,7 @@ vi 3rd/include/libxml2/libxml/xmlversion.h
做好上面的准备工作，还需要修改源码中的路径配置，然后才能正常编译。
下面都是我踩坑留下的记录。

1. 修改 configure/RELEASE
1. 修改 `configure/RELEASE`

``` shell
cd ethercat-master/
Expand All @@ -408,7 +408,7 @@ EPICS_HOST_ARCH=linux-la64
EPICS_BASE=/home/ubuntu/loongson/base-7.0.8
```

2. 修改 ethercatApp/scannerSrc/Makefile
2. 修改 `ethercatApp/scannerSrc/Makefile`

``` shell
cd ethercat-master/
Expand Down Expand Up @@ -438,7 +438,7 @@ serialtool_INCLUDES += -I$(ETHERLAB)/master
get-slave-revisions_INCLUDES += -I$(ETHERLAB)/master
```

3. 修改 ethercatApp/src/Makefile，与上面类似。
3. 修改 `ethercatApp/src/Makefile`，与上面类似。

``` shell
cd ethercat-master/
Expand All @@ -463,7 +463,131 @@ USR_LDFLAGS += -L$(TOP)/3rd/lib -Wl,-rpath=$(TOP)/3rd/lib
USR_SYS_LIBS += xml2
```

4. 编译
4. 修改源码

由于`ethercat-master`的源码原本是为`x86_64`架构编写的，编译到`LoongArch`架构的设备上运行可能会出现一些奇怪的错误。

例如，在运行`slaveinfo`时会出现`Segmentation fault`错误，通常是**空指针**导致内存访问出错。

原因分析：

`slaveinfo`在运行时会根据程序自己的路径寻找`slave-types.txt`文件，问题就出在这里。来看源码 `ethercatApp/scannerSrc/slave-list-path.c`。

``` c
// ethercatApp/scannerSrc/slave-list-path.c

int get_root_dir_index(const char *program_name)
{
// Search for the binary path
char binary_dir[] = "bin/linux-x86_64/";

// Find the binary path in the program path and return the pointer
char *found = strstr(program_name, binary_dir);

// Handle the case where it is not found
if (found == NULL)
{
return -1;
}

// Calculate the difference in the pointers to get the index
return found - program_name;
}
```
这个`get_root_dir_index`函数是用于计算当前程序(`slaveinfo`)所在的**根**目录。这里向上查找的路径为`bin/linux-x86_64`，当然不能找到`LoongArch`的目录`bin/linux-la64`了。所以，此函数只在路径为`bin/linux-x86_64/slaveinfo`时才能正常运行，其它情况都返回`-1`。（第一次见到这样写的，真无语了……）
``` c
// ethercatApp/scannerSrc/slave-list-path.c
char *get_slave_list_filename(const char *program_path)
{
char relative_path[] = "etc/scripts/slave-types.txt";
char *slave_list_filename = NULL;
// Get absolute path of application
char *real_path = calloc(PATH_MAX, sizeof(char));
get_app_path(program_path, real_path);
// Get root directory
int root_dir_index = get_root_dir_index(real_path);
if (root_dir_index != -1)
{
slave_list_filename = calloc(root_dir_index + strlen(relative_path) + 1, sizeof(char));
strncpy(slave_list_filename, real_path, root_dir_index);
}
// Append relative path
strcat(slave_list_filename, relative_path);
// Check file
struct stat fstat;
int result = stat(slave_list_filename, &fstat);
if (result)
{
printf("Could not find slave list file at %s\n", slave_list_filename);
}
// Cleanup
free(real_path);
return slave_list_filename;
}
```

而在`get_slave_list_filename`函数中，只处理了`get_root_dir_index`返回正常时的情况。当`get_root_dir_index`返回`-1`时，`slave_list_filename`始终为`NULL`，这就导致后续操作出错。

其实这个问题直接把程序放到`bin/linux-x86_64`目录下运行就可以了，不过既然找到了问题，索性就改一改。

现在已经知道了出错的地方，该如何修改呢？这里我本着尽量少改动源码的原则，在`get_root_dir_index`查找**根**目录出错时，直接使用当前目录。

``` diff
char *get_slave_list_filename(const char *program_path)
{
char relative_path[] = "etc/scripts/slave-types.txt";
char *slave_list_filename = NULL;

// Get absolute path of application
char *real_path = calloc(PATH_MAX, sizeof(char));
get_app_path(program_path, real_path);

// Get root directory
int root_dir_index = get_root_dir_index(real_path);
if (root_dir_index != -1)
{
slave_list_filename = calloc(root_dir_index + strlen(relative_path) + 1, sizeof(char));
strncpy(slave_list_filename, real_path, root_dir_index);
}
+ else
+ {
+ slave_list_filename = calloc(PATH_MAX, sizeof(char));
+ if (NULL != getcwd(slave_list_filename, PATH_MAX))
+ {
+ strcat(slave_list_filename, "/");
+ }
+ }

// Append relative path
strcat(slave_list_filename, relative_path);

// Check file
struct stat fstat;
int result = stat(slave_list_filename, &fstat);
if (result)
{
printf("Could not find slave list file at %s\n", slave_list_filename);
}

// Cleanup
free(real_path);

return slave_list_filename;
}
```

目前只发现了这个问题，希望后面没有坑了。

5. 编译

最后终于可以开始编译了。

Expand All @@ -474,19 +598,23 @@ make LD=loongarch64-linux-gnu-ld CC=loongarch64-linux-gnu-gcc CCC=loongarch64-li
```

到这里，编译过程还可能会出错，不过已经可以编译出我们所需要的东西了。
最终编译得到`scanner`程序就可以了。
最终编译得到`scanner`、`slaveinfo`程序就可以了。

以下是我编译时的输出：

``` shell
...
Installing library ../../../lib/linux-la64/libscannerlib.a
...
Installing created executable ../../../bin/linux-la64/serialtool
Installing created executable ../../../bin/linux-la64/get-slave-revisions
Installing created executable ../../../bin/linux-la64/scanner
Installing created executable ../../../bin/linux-la64/slaveinfo
Installing created executable ../../../bin/linux-la64/parsertest
...
Installing shared library ../../../lib/linux-la64/libecAsyn.so
Installing library ../../../lib/linux-la64/libecAsyn.a
Installing created executable ../../../bin/linux-la64/parsertest
...
Installing template file ../../../db/EK1100.template
...
Expand Down Expand Up @@ -653,9 +781,9 @@ fi
# check for modules to replace
for MODULE in ${DEVICE_MODULES}; do
ECMODULE=ec_${MODULE}
if ! ${MODINFO} "${ECMODULE}" > /dev/null; then
continue # ec_* module not found
fi
- if ! ${MODINFO} "${ECMODULE}" > /dev/null; then
- continue # ec_* module not found
- fi
if [ "${MODULE}" != "generic" ]; then
if ${LSMOD} | grep "^${MODULE} " > /dev/null; then
if ! ${RMMOD} "${MODULE}"; then
Expand Down Expand Up @@ -690,6 +818,11 @@ IP=/bin/ip
+ ETHERCAT=/usr/bin/ethercat
+ MODULE_DIR=/root/modules

#------------------------------------------------------------------------------

- ETHERCAT_CONFIG=/home/loongson/__install_dir/etc/ethercat.conf
+ ETHERCAT_CONFIG=/etc/ethercat.conf

start)

...
Expand All @@ -703,7 +836,22 @@ fi

LOADED_MODULES=ec_master

...
# check for modules to replace
for MODULE in ${DEVICE_MODULES}; do
ECMODULE=ec_${MODULE}
- if ! ${MODINFO} "${ECMODULE}" > /dev/null; then
- continue # ec_* module not found
- fi

if [ "${MODULE}" != "generic" ] && [ "${MODULE}" != "ccat" ]; then
# unload standard module and check if unloading was successful
${RMMOD} "${MODULE}" 2> /dev/null || true
if ${LSMOD} | grep "^${MODULE} " > /dev/null; then
# could not unload module
${RMMOD} ${LOADED_MODULES}
exit 1
fi
fi

- if ! ${MODPROBE} ${MODPROBE_FLAGS} "${ECMODULE}"; then
+ if ! ${INSMOD} "${MODULE_DIR}/${ECMODULE}.ko"; then
Expand Down

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