Examine the symbolized logs (that is, human readable stack traces) of a crashed component.

The tasks include:

• Update the sample component to crash when it's started.
• Build and run the sample component, which generates and registers the debug symbols of the component.
• Verify that the crashed component's logs are in symbolized format.

Do the following:

1. Use a text editor to edit the src/hello_world/hello_world.cc file, for example:

   nano src/hello_world/hello_world.cc
   

2. Above the line return 0;, add the following line:

   abort();
   

   The main() method now should look like below:

   int main() {
     std::cout << "Hello again, World!\n";
     {{ '<strong>' }}abort();{{ '</strong>' }}
     return 0;
   }
   

   This update will cause the component to crash immediately after printing a message.

3. Save the file and exit the text editor.

4. Build and run the sample component:

   tools/bazel run //src/hello_world:pkg.component
   

   Building a component automatically generates and registers its debug symbols in the development environment.

5. Restart the ffx daemon:

   Note: Today, this workaround is required for newly registered symbols to be discovered in the environment. This issue is being tracked in Issue 94614{:.external}.

   tools/ffx daemon stop
   

   A new instance of the ffx daemon starts the next time you run a ffx command.

6. Verify that the sample component's crash stack is symbolized in the kernel logs:

   tools/ffx log --kernel
   

   This command prints output similar to the following:

   $ tools/ffx log --kernel
   ...
   [174978.449][klog][klog][I] [[[ELF module #0x6 "libzircon.so" BuildID=5679a47f32c6fa7b 0x422808b26000]]]
   [174978.449][klog][klog][I] [[[ELF module #0x7 "libc.so" BuildID=1c3e8dded0fc94eb 0x428049099000]]]
   [174978.450][klog][klog][I]    #0    0x00004280490fd74b in abort() ../../zircon/third_party/ulib/musl/src/exit/abort.c:7 <libc.so>+0x6474b sp 0x11d191bcf70
   {{ '<strong>' }}[174978.450][klog][klog][I]    #1    0x000001d56b552047 in main() src/hello_world/hello_world.cc:9 <<VMO#32996646=blob-a4c56246>>+0x2047 sp 0x11d191bcf80{{ '</strong>' }}
   [174978.450][klog][klog][I]    #2    0x00004280490fcef2 in start_main(const start_params*) ../../zircon/third_party/ulib/musl/src/env/__libc_start_main.c:140 <libc.so>+0x63ef2 sp 0x11d191bcfa0
   [174978.450][klog][klog][I]    #3    0x00004280490fd145 in __libc_start_main(zx_handle_t, int (*)(int, char**, char**)) ../../zircon/third_party/ulib/musl/src/env/__libc_start_main.c:215 <libc.so>+0x64145 sp 0x11d191bcff0
   [174978.450][klog][klog][I]    #4    0x000001d56b552011 in _start(zx_handle_t) ../../zircon/system/ulib/c/Scrt1.cc:7 <<VMO#32996646=blob-a4c56246>>+0x2011 sp 0x42d5c7089fe0
   [174978.450][klog][klog][I]    #5    0x0000000000000000 is not covered by any module sp 0x42d5c7089ff0
   [174978.457][klog][klog][I] KERN: terminating process 'hello_world.cm' (32996655)
   

   The symbolized logs above show the exact filenames and line numbers (for example, main() src/hello_world/hello_world.cc:9) that might have caused the component to crash.

   Press CTRL+C to exit.