调试支持 GDB stub 的 Client OS¶

当前仅支持调试运行在树莓派4B（aarch64）和x86工控机（x86_64）的Uniproton。

基于树莓派4B调测Uniproton¶

树莓派4B的具体介绍树莓派4B 。

树莓派的openeuler-image-mcs构建，参见树莓派mcs镜像构建指导。由于需要调试，需要在oebuild构建目录中的conf文件夹下的local.conf文件中添加如下配置：

# Enable Debugging Features, like including gdb binary in the image
IMAGE_FEATURE += "debug-tweaks"

当然，也可以在openeuler-image-mcs.bb文件中临时增加上述配置。

编译好了树莓派的openeuler-image-mcs镜像并烧录到sd卡，在树莓派上启动后，配置好UEFI，之后进入系统。

此时，输入如下命令，查看当前系统中支持的RTOS：

$ mica status
Name                          Assigned CPU        State               Service
uniproton                     3                   Offline
uniproton-gdb                 3                   Offline

其中，uniproton-gdb是支持GDB stub的Uniproton。它的conf文件的路径为 /etc/mica/rpi4-uniproton-gdb.conf 。这里，有一个很重要的配置选项 Debug=yes ，表示此实例支持GDB stub。

输入如下命令启动支持GDB stub的Uniproton：

$ mica start uniproton-gdb
starting uniproton-gdb...
start uniproton-gdb successfully!

此时，可以通过启动GDB Client连接到MICA GDB server，以调测Uniproton内核：

$ mica gdb uniproton-gdb
gdb /root/raspi4.elf -ex 'target extended-remote :5678' -ex 'set remote run-packet off' -ex 'set remotetimeout unlimited'
GNU gdb (GDB) 14.1
Copyright (C) 2023 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "aarch64-openeuler-linux".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /root/raspi4.elf...
Remote debugging using :5678
warning: Remote gdbserver does not support determining executable automatically.
RHEL <=6.8 and <=7.2 versions of gdbserver do not support such automatic executable detection.
The following versions of gdbserver support it:
- Upstream version of gdbserver (unsupported) 7.10 or later
- Red Hat Developer Toolset (DTS) version of gdbserver from DTS 4.0 or later (only on x86_64)
- RHEL-7.3 versions of gdbserver (on any architecture)
0x000000007b025eb4 in OsGdbArchInit ()
Support for the 'vRun' packet on the current remote target is set to "off".
(gdb)

第一行打印的gdb命令是输入 mica gdb <name> 后所实际执行的gdb命令，用户可以依据此提示进一步调试。之后，用户进入GDB命令行，可以执行相应的GDB命令。接下来会演示一些当前Uniproton支持的调测命令：

(gdb) b OsTestInit
warning: could not convert 'OsTestInit' from the host encoding (ANSI_X3.4-1968) to UTF-32.
This normally should not happen, please file a bug report.
Breakpoint 1 at 0x7b007b4c: file /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c, line 42.
(gdb) c
Continuing.

Breakpoint 1, OsTestInit () at /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c:42
warning: 42     /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c: No such file or directory
(gdb) s
43      in /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c
(gdb) p param
$1 = {taskEntry = 0x0, taskPrio = 0, reserved = 0, args = {0, 0, 0, 2063689196},
stackSize = 2063629368,
name = 0x2307b01dd48 <error: Cannot access memory at address 0x2307b01dd48>, stackAddr = 2064460304}
(gdb) s
45      in /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c
(gdb) p param
$2 = {taskEntry = 0x0, taskPrio = 0, reserved = 0, args = {0, 0, 0, 0}, stackSize = 0, name = 0x0,
stackAddr = 0}
(gdb) watch param.taskPrio
Hardware watchpoint 2: param.taskPrio
(gdb) c
Continuing.

Hardware watchpoint 2: param.taskPrio

Old value = 0
New value = 25
OsTestInit () at /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c:48
48      in /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c
(gdb) c
Continuing.

Watchpoint 2 deleted because the program has left the block in
which its expression is valid.
0x000000007b007c54 in PRT_AppInit ()
    at /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c:86
86      in /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c
(gdb) c
Continuing.
^C
Program received signal SIGINT, Interrupt.
0x000000007b01da84 in PRT_SemPend ()
(gdb) run
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /root/raspi4.elf
warning: Remote gdbserver does not support determining executable automatically.
RHEL <=6.8 and <=7.2 versions of gdbserver do not support such automatic executable detection.
The following versions of gdbserver support it:
- Upstream version of gdbserver (unsupported) 7.10 or later
- Red Hat Developer Toolset (DTS) version of gdbserver from DTS 4.0 or later (only on x86_64)
- RHEL-7.3 versions of gdbserver (on any architecture)

Breakpoint 1, OsTestInit () at /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c:42
warning: 42     /home/zzz/repo/private/UniProton/demos/raspi4/apps/openamp/main.c: No such file or directory
(gdb)

首先，通过 break 命令在 OsTestInit 函数处设置断点，之后通过 continue 命令继续执行。
在 OsTestInit 函数处，通过 print 命令查看 param 结构体的内容，之后通过 step 命令逐行执行。
在 param.taskPrio 变量处，通过 watch 命令设置硬件监视点，之后通过 continue 命令继续执行。
在 param.taskPrio 变量发生变化时，GDB会停止执行。当代码执行的区域超出了 param.taskPrio 变量所处的区域，GDB也会停止执行。
通过执行 continue，RTOS持续运行了起来。之后可以通过 ctrl-c 命令停止执行。
之后，可以通过 run 命令重新加载并启动RTOS，Uniproton会在第一个断点处停止执行。

输入 quit 命令退出GDB调试模式，之后，Uniproton会清除所有断点，并进入正常的运行状态。之后，如果想停止Uniproton，可以输入如下命令：

$ mica stop uniproton-gdb
stopping uniproton-gdb...
stop uniproton-gdb successfully!

Note

由于Uniproton在GDB stub方面的具体实现方式，如果Uniproton正在等待GDB client的连接，它还没有初始化中断，所以在这个阶段，Uniproton不会响应系统停止的指令。因此，此时发送 mica stop <name> 命令是无效的。

基于x86工控机调测Uniproton¶

工控机的具体介绍工控机。

使用方法¶

首先，需要构建含有MICA的openEuler Embedded镜像，请参考 MICA镜像构建指南。

然后，需要生成适配了GDB stub 的 Uniproton，参考 UniProton GDB stub 构建指南。

在运行命令时，需要在启动MICA时加上 -d 参数。并且，由于需要对可执行文件进行调试， -t 参数需要指定包含符号表的可执行文件的路径。一般来说，plain binary format的可执行文件并没有相关调试信息，所以我们只能使用elf格式的可执行文件进行调试。当然，如果 -t 参数指定的是格式为plain binary format的可执行文件的路径，调试模式仍然可以正常启动，但是在启动GDB client的时候无法正确读取符号表，需要用 file 命令额外指定包含符号表的可执行文件的路径。

以下是启动MICA调试模式的命令：

# 若使用的是标准镜像，则使用mica脚本启动MICA：
$ mica start /path/to/executable -d
# 若没有mica脚本，则使用如下命令启动MICA：
$ insmod /path/to/mcs_km.ko rmem_base=0x118000000 rmem_size=0x10000000
# 启动MICA调试模式：
$ /path/to/mica_main -c 3 -t /path/to/executable -a 0x118000000 -b /path/to/ap_boot -d
...
MICA gdb proxy server: starting...
GNU gdb (GDB) 12.1
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-openeuler-linux".
...
MICA gdb proxy server: read for messages forwarding ...
(gdb)

此时，用户可以直接通过GDB命令行输入命令与Client OS进行交互。如果用户想要通过GDB命令行像正常情况一样运行client OS，可以直接不设置断点，输入命令 continue 。

按下 ctrl-c 之后会返回GDB命令行，此时用户可以输入GDB命令与Client OS进行交互。如果用户想要退出调试模式，必须在GDB命令行输入 quit 命令。之后， MICA会退出与调试相关的模块，并保留pty application模块，以保持和Client OS通过pty交互的能力。 Uniproton会清除所有断点，并进入正常的运行状态。

Note

当前Uniproton的GDB stub支持 break， continue， print ， quit ， backtrace， watch， step， run 和 ctrl-c 九个命令。

调试支持 GDB stub 的 Client OS¶

基于树莓派4B调测Uniproton¶

基于x86工控机调测Uniproton¶

相关接口定义¶

使用方法¶