1# LLDB 2## Overview 3Low Lever Debugger (LLDB) is a next-generation, high-performance debugger. For details, visit the [LLDB official website](https://lldb.llvm.org/). 4 5LLDB used in OpenHarmony is developed on [LLVM 15.0.4](https://github.com/llvm/llvm-project/releases/tag/llvmorg-15.0.4). It is the default debugger in DevEco Studio and supports debugging of C and C++ applications. 6 7## How to Obtain 8Obtain the OpenHarmony SDK from the following website: http://ci.openharmony.cn/workbench/cicd/dailybuild 9 10Find LLDB in the **\ohos-sdk\[system]\native\llvm** directory of the SDK, where **system** can be **windows**, **linux**, or **darwin**. 11 12For example, for Windows, **lldb.exe** is stored in **\ohos-sdk\windows\native\llvm\bin** after the SDK is decompressed. 13 14## Functions 15 16The following lists some functions supported by LLDB. For more functions and related commands, see [LLDB Usage Guide](https://gitee.com/openharmony/third_party_llvm-project/blob/master/lldb/README.md) and [LLDB official manual](https://lldb.llvm.org/use/map.html#). 17 18- Logging 19 20- Breakpoint management 21 22- Watchpoint management 23 24- Expression processing 25 26- Viewing variables 27 28- Process/Thread management 29 30- Assembly processing 31 32- Obtaining source code information 33 34- Signal processing 35 36- Launching a process 37 38- Attaching to a process 39 40## Use Scenarios 41 42### Local Debugging 43 44- Linux x86_64 local debugging 45 46 LLDB supports debugging of C and C++ applications in the Linux x86_64 environment. 47 48- macOS local debugging on the macOS desktop 49 50 LLDB supports debugging of C and C++ applications on the macOS desktop (including macOS x86_64 and M1). 51 52### Remote Debugging 53 54- Remote debugging based on DevEco Studio 55 56 LLDB supports remote debugging of native C++ applications by connecting to OpenHarmony devices or emulators on the Windows and macOS desktops based on DevEco Studio. 57 58- Remote debugging through direct connection 59 60 LLDB supports remote debugging of C and C++ applications by directly connecting to OpenHarmony devices in Windows, macOS desktop, and Linux x86_64 environment. 61 62## How to Use 63 64### Local Debugging 65 66> **NOTE** 67> 68> The local debugging procedure for Linux x86_64 is the same as that for macOS. 69 70**Procedure** 71 72- Using LLDB to start and debug an application 73 74 The following walks you through on how to debug an executable file named **a.out** in the Linux x86_64 environment. The file contains debugging information and is generated by the Clang compiler, which is of the same version as LLDB. 75 76 1. Obtain the executable file **a.out**. 77 78 2. Run LLDB and specify the file to debug as **a.out**. 79 80 ```lldb 81 ./lldb a.out 82 ``` 83 84 3. Set breakpoints at the **main** function in the code. 85 86 ```lldb 87 (lldb) b main 88 ``` 89 90 4. Run the application, and it stops at the first breakpoint. 91 92 ```lldb 93 (lldb) run 94 ``` 95 96 5. Continue to run the application. 97 98 ```lldb 99 (lldb) continue 100 ``` 101 102 6. List all the breakpoints. 103 104 ```lldb 105 (lldb) breakpoint list 106 ``` 107 108 7. Show the arguments and local variables of the current frame. 109 110 ```lldb 111 (lldb) frame variable 112 ``` 113 114 8. Run debugging commands as required to continue debugging. 115 116 9. Exit debugging. 117 118 ```lldb 119 (lldb) quit 120 ``` 121 122- Using LLDB to debug a started application 123 124 The following walks you through on how to debug an executable file named **a.out** in the macOS environment. The file contains user input and debugging information and is generated by the Clang compiler. 125 126 1. Start the application on Command Line Interface (CLI) 1. (The message "Please input a number of type int" is displayed.) 127 ```shell 128 ./a.out 129 ``` 130 131 2. Run LLDB on CLI 2. 132 ```shell 133 ./lldb 134 ``` 135 136 3. Attach to the application. 137 138 ```lldb 139 (lldb) process attach --name a.out 140 ``` 141 142 4. Set a breakpoint in line 10 of **hello.cpp**. 143 144 ```lldb 145 (lldb) breakpoint set --file hello.cpp --line 12 146 ``` 147 148 5. On CLI 1, enter a number of the int type. 149 150 ```shell 151 88 152 ``` 153 154 6. Continue to run the application on CLI 2. The application stops at the breakpoint. 155 156 ````lldb 157 (lldb) continue 158 ```` 159 160 7. Run debugging commands as required to continue debugging. 161 162 8. Detach from the application. 163 164 ```lldb 165 (lldb) detach 166 ``` 167 168 9. Exit debugging. 169 170 ```lldb 171 (lldb) quit 172 ``` 173 174 > **NOTE** 175 > 176 > You can also perform step 4 in prior to step 3. 177 178 179### Remote Debugging 180 181> **NOTE** 182> 183> - During remote debugging, **lldb-server** and **lldb** must be used together. 184> - The remote debugging procedures for Windows, Linux x86_64, and macOS are the same. 185> 186 187**Procedure** 188 189The following walks you through on how to remotely debug an executable file named **a.out** by connecting to an ARM-based OpenHarmony device (for example, RK3568 development board) on the Windows platform. 190 191> **NOTE** 192> 193> In the command below, **/data/local/tmp** indicates the specified directory on the device. 194> 195> **8080** is the listening port, which can be customized. 196> 197> You must have the execute permission on the **lldb-server** and **a.out** files of the device. 198> 199 2001. Open CLI 1 and push **lldb-server** and **a.out** to the device. (**a.out** is generated when you compile **hello.cpp** using the Clang compiler.) 201 202 ```shell 203 hdc file send lldb-server /data/local/tmp 204 hdc file send a.out /data/local/tmp 205 ``` 206 2072. Run **lldb-server**. 208 209 ```shell 210 hdc shell ./data/local/tmp/lldb-server p --server --listen "*:8080" 211 ``` 212 2133. Open CLI 2 and run the binary file **lldb**. 214 215 ```shell 216 ./lldb 217 ``` 218 2194. Select and connect to the remote device on the LLDB CLI. 220 221 ```lldb 222 (lldb) platform select remote-ohos 223 (lldb) platform connect connect://localhost:8080 224 ``` 225 2265. Specify the binary file **a.out** on the device to be debugged. 227 228 ```lldb 229 (lldb) target create /data/local/tmp/a.out 230 ``` 231 2326. Set breakpoints at the **main** function in the code. 233 234 ```lldb 235 (lldb) b main 236 ``` 237 2387. Start the application. 239 240 ```lldb 241 (lldb) run 242 ``` 243 2448. Display source code for the current target process. 245 246 ```lldb 247 (lldb) source list 248 ``` 249 2509. Run debugging commands as required to continue debugging. 251 25210. Exit debugging. 253 254 ```lldb 255 (lldb) quit 256 ``` 257