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Diffstat (limited to 'nixpkgs/doc/stdenv/stdenv.chapter.md')
| -rw-r--r-- | nixpkgs/doc/stdenv/stdenv.chapter.md | 53 |
1 files changed, 48 insertions, 5 deletions
diff --git a/nixpkgs/doc/stdenv/stdenv.chapter.md b/nixpkgs/doc/stdenv/stdenv.chapter.md index 15cb081a04e2..366c519751c0 100644 --- a/nixpkgs/doc/stdenv/stdenv.chapter.md +++ b/nixpkgs/doc/stdenv/stdenv.chapter.md @@ -991,13 +991,56 @@ Hook executed at the end of the fixup phase. If set to `true`, the standard environment will enable debug information in C/C++ builds. After installation, the debug information will be separated from the executables and stored in the output named `debug`. (This output is enabled automatically; you don’t need to set the `outputs` attribute explicitly.) To be precise, the debug information is stored in `debug/lib/debug/.build-id/XX/YYYY…`, where \<XXYYYY…\> is the \<build ID\> of the binary — a SHA-1 hash of the contents of the binary. Debuggers like GDB use the build ID to look up the separated debug information. -For example, with GDB, you can add +:::{.example #ex-gdb-debug-symbols-socat} +# Enable debug symbols for use with GDB + +To make GDB find debug information for the `socat` package and its dependencies, you can use the following `shell.nix`: + +```nix +let + pkgs = import ./. { + config = {}; + overlays = [ + (final: prev: { + ncurses = prev.ncurses.overrideAttrs { separateDebugInfo = true; }; + readline = prev.readline.overrideAttrs { separateDebugInfo = true; }; + }) + ]; + }; + + myDebugInfoDirs = pkgs.symlinkJoin { + name = "myDebugInfoDirs"; + paths = with pkgs; [ + glibc.debug + ncurses.debug + openssl.debug + readline.debug + ]; + }; +in + pkgs.mkShell { + + NIX_DEBUG_INFO_DIRS = "${pkgs.lib.getLib myDebugInfoDirs}/lib/debug"; + + packages = [ + pkgs.gdb + pkgs.socat + ]; + + shellHook = '' + ${pkgs.lib.getBin pkgs.gdb}/bin/gdb ${pkgs.lib.getBin pkgs.socat}/bin/socat + ''; + } ``` -set debug-file-directory ~/.nix-profile/lib/debug -``` -to `~/.gdbinit`. GDB will then be able to find debug information installed via `nix-env -i`. +This setup works as follows: +- Add [`overlays`](#chap-overlays) to the package set, since debug symbols are disabled for `ncurses` and `readline` by default. +- Create a derivation to combine all required debug symbols under one path with [`symlinkJoin`](#trivial-builder-symlinkJoin). +- Set the environment variable `NIX_DEBUG_INFO_DIRS` in the shell. Nixpkgs patches `gdb` to use it for looking up debug symbols. +- Run `gdb` on the `socat` binary on shell startup in the [`shellHook`](#sec-pkgs-mkShell). Here we use [`lib.getBin`](#function-library-lib.attrsets.getBin) to ensure that the correct derivation output is selected rather than the default one. + +::: ### The installCheck phase {#ssec-installCheck-phase} @@ -1478,7 +1521,7 @@ This flag can break dynamic shared object loading. For instance, the module syst #### `bindnow` {#bindnow} -Adds the `-z bindnow` linker option. During program load, all dynamic symbols are resolved, allowing for the complete GOT to be marked read-only (due to `relro`). This prevents GOT overwrite attacks. For very large applications, this can incur some performance loss during initial load while symbols are resolved, but this shouldn’t be an issue for daemons. +Adds the `-z now` linker option. During program load, all dynamic symbols are resolved, allowing for the complete GOT to be marked read-only (due to `relro`). This prevents GOT overwrite attacks. For very large applications, this can incur some performance loss during initial load while symbols are resolved, but this shouldn’t be an issue for daemons. This flag can break dynamic shared object loading. For instance, the module systems of Xorg and PHP are incompatible with this flag. Programs incompatible with this flag often fail at runtime due to missing symbols, like: |