mirror of
https://github.com/NixOS/nix
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73 lines
1.8 KiB
Markdown
73 lines
1.8 KiB
Markdown
# Debugging Nix
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This section shows how to build and debug Nix with debug symbols enabled.
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Additionally, see [Testing Nix](./testing.md) for further instructions on how to debug Nix in the context of a unit test or functional test.
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## Building Nix with Debug Symbols
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In the development shell, set the `mesonBuildType` environment variable to `debug` before configuring the build:
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```console
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[nix-shell]$ export mesonBuildType=debugoptimized
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```
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Then, proceed to build Nix as described in [Building Nix](./building.md).
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This will build Nix with debug symbols, which are essential for effective debugging.
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It is also possible to build without debugging for faster build:
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```console
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[nix-shell]$ NIX_HARDENING_ENABLE=$(printLines $NIX_HARDENING_ENABLE | grep -v fortify)
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[nix-shell]$ export mesonBuildType=debug
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```
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(The first line is needed because `fortify` hardening requires at least some optimization.)
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## Debugging the Nix Binary
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Obtain your preferred debugger within the development shell:
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```console
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[nix-shell]$ nix-shell -p gdb
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```
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On macOS, use `lldb`:
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```console
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[nix-shell]$ nix-shell -p lldb
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```
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### Launching the Debugger
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To debug the Nix binary, run:
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```console
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[nix-shell]$ gdb --args ../outputs/out/bin/nix
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```
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On macOS, use `lldb`:
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```console
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[nix-shell]$ lldb -- ../outputs/out/bin/nix
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```
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### Using the Debugger
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Inside the debugger, you can set breakpoints, run the program, and inspect variables.
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```gdb
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(gdb) break main
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(gdb) run <arguments>
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```
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Refer to the [GDB Documentation](https://www.gnu.org/software/gdb/documentation/) for comprehensive usage instructions.
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On macOS, use `lldb`:
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```lldb
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(lldb) breakpoint set --name main
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(lldb) process launch -- <arguments>
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```
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Refer to the [LLDB Tutorial](https://lldb.llvm.org/use/tutorial.html) for comprehensive usage instructions.
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