Debug Symbols - Revision history

Tbertels: /* nixseparatedebuginfo */ Update to nixseparatedebuginfod2

2026-01-12T12:48:26Z

nixseparatedebuginfo: Update to nixseparatedebuginfod2

← Older revision		Revision as of 12:48, 12 January 2026
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	==== nixseparatedebuginfo ====		==== nixseparatedebuginfo ====
	[https://github.com/symphorien/~~nixseparatedebuginfod nixseparatedebuginfod~~] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. Gdb is built with support for debuginfod, and valgrind has support if you additionally install the bin output of elfutils.		[https://github.com/symphorien/nixseparatedebuginfod2 nixseparatedebuginfod2] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. Gdb is built with support for debuginfod, and valgrind has support if you additionally install the bin output of elfutils.

	[[Category:Nixpkgs]]		[[Category:Nixpkgs]]

Pigs: Add category nixpkgs

2025-05-18T16:43:58Z

Add category nixpkgs

← Older revision		Revision as of 16:43, 18 May 2025
Line 133:		Line 133:
	==== nixseparatedebuginfo ====		==== nixseparatedebuginfo ====
	[https://github.com/symphorien/nixseparatedebuginfod nixseparatedebuginfod] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. Gdb is built with support for debuginfod, and valgrind has support if you additionally install the bin output of elfutils.		[https://github.com/symphorien/nixseparatedebuginfod nixseparatedebuginfod] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. Gdb is built with support for debuginfod, and valgrind has support if you additionally install the bin output of elfutils.

			[[Category:Nixpkgs]]

Mic92: drop 23.05

2024-12-03T08:54:46Z

drop 23.05

← Older revision		Revision as of 08:54, 3 December 2024
Line 132:		Line 132:

	==== nixseparatedebuginfo ====		==== nixseparatedebuginfo ====
	[https://github.com/symphorien/nixseparatedebuginfod nixseparatedebuginfod] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. ~~Since NixOS 23.05, gdb~~ is built with support for debuginfod, and valgrind has support if you additionally install the bin output of elfutils. On earlier releases, support must be overridden by hand, for example instead of installing <code>gdb</code> in <code>/etc/nixos/configuration.nix</code>, you should install <code>(gdb.override { enableDebuginfod = true })</code>.		[https://github.com/symphorien/nixseparatedebuginfod nixseparatedebuginfod] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. Gdb is built with support for debuginfod, and valgrind has support if you additionally install the bin output of elfutils.

imported>Symphorien: gdb is now built with debuginfod support.

2024-01-02T21:32:43Z

gdb is now built with debuginfod support.

← Older revision		Revision as of 21:32, 2 January 2024
Line 132:		Line 132:

	==== nixseparatedebuginfo ====		==== nixseparatedebuginfo ====
	[https://github.com/symphorien/nixseparatedebuginfod nixseparatedebuginfod] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. ~~As of~~ NixOS 22.11, ~~only hotspot~~ is built with debuginfod support by ~~default~~, ~~and notably not gdb so~~ instead of installing <code>gdb</code> in <code>/etc/nixos/configuration.nix</code>, you should install <code>(gdb.override { enableDebuginfod = true })</code>.		[https://github.com/symphorien/nixseparatedebuginfod nixseparatedebuginfod] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. Since NixOS 23.05, gdb is built with support for debuginfod, and valgrind has support if you additionally install the bin output of elfutils. On earlier releases, support must be overridden by hand, for example instead of installing <code>gdb</code> in <code>/etc/nixos/configuration.nix</code>, you should install <code>(gdb.override { enableDebuginfod = true })</code>.

imported>Symphorien: mention nixseparatedebuginfod

2023-02-25T13:53:08Z

mention nixseparatedebuginfod

← Older revision		Revision as of 13:53, 25 February 2023
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	==== dwarffs ====		==== dwarffs ====
	To avoid the need to explicitly list every dependency in <code>environment.systemPackages</code> to have its debug output available, you can use [https://github.com/edolstra/dwarffs dwarffs]. It will create a virtual file system where gdb will be able to look for separate debug symbols for packages on-demand. The downside is that it might increase gdb start up time significantly.		To avoid the need to explicitly list every dependency in <code>environment.systemPackages</code> to have its debug output available, you can use [https://github.com/edolstra/dwarffs dwarffs]. It will create a virtual file system where gdb will be able to look for separate debug symbols for packages on-demand. The downside is that it might increase gdb start up time significantly.

			==== nixseparatedebuginfo ====
			[https://github.com/symphorien/nixseparatedebuginfod nixseparatedebuginfod] is a debuginfod server that can download the relevant debug outputs and source files as needed by debuginfod-capable tools. Compared to dwarffs, it does not require root access, and handles debug outputs of derivations not built by hydra (eg locally or on a custom binary cache) and source files. As of NixOS 22.11, only hotspot is built with debuginfod support by default, and notably not gdb so instead of installing <code>gdb</code> in <code>/etc/nixos/configuration.nix</code>, you should install <code>(gdb.override { enableDebuginfod = true })</code>.

imported>Jtojnar: Mention dwarffs

2022-04-17T03:18:37Z

Mention dwarffs

← Older revision		Revision as of 03:18, 17 April 2022
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	==== NixOS ====		==== NixOS ====
	By toggling <code>environment.enableDebugInfo</code> to 'true' in <code>/etc/nixos/configuration.nix</code>, all		By toggling <code>environment.enableDebugInfo</code> to 'true' in <code>/etc/nixos/configuration.nix</code>, all separate debug info derivations in your <code>systemPackages</code> will have their debug output linked in <code>/run/current-system/sw/lib/debug/</code> and will be automatically available to gdb. Though note that this will not pick up debug symbols of dependencies – you will need to add the dependencies you want to debug to <code>environment.systemPackages</code> explicitly. If a derivation you are interested in does not have separate debug info enabled, you still have to override it with an overlay for example.
	separate debug info derivations in your <code>systemPackages</code> will have their debug output linked in <code>/run/current-system/sw/lib/debug/</code> and
	will be automatically available to gdb. If a derivation you are interested in does not have separate debug info enabled, you		==== dwarffs ====
	still have to override it with an overlay for example.		To avoid the need to explicitly list every dependency in <code>environment.systemPackages</code> to have its debug output available, you can use [https://github.com/edolstra/dwarffs dwarffs]. It will create a virtual file system where gdb will be able to look for separate debug symbols for packages on-demand. The downside is that it might increase gdb start up time significantly.

imported>Symphorien: /* Unstripped packages */ mention the difference between dontStrip and enableDebugging

2018-12-02T23:51:44Z

Unstripped packages: mention the difference between dontStrip and enableDebugging

← Older revision		Revision as of 23:51, 2 December 2018
Line 7:		Line 7:
	Two types of packages can provide debug symbols:		Two types of packages can provide debug symbols:
	==== Unstripped packages ====		==== Unstripped packages ====
			To prevent stripping of a derivation, use the option <code>dontStrip = true;</code>. This still compiles with optimisation;
			to compile with <code>-Og -ggdb</code> in addition to disabling stripping, you can use the function <code>enableDebugging</code>.
	Let's take the example of <code>socat</code>.		Let's take the example of <code>socat</code>.

	If you install socat, then run		If you install socat, then run
	{{Commands\|		{{Commands\|
Line 30:		Line 31:
	you see that you have debugging symbols for neither socat itself nor for dependent libraries.		you see that you have debugging symbols for neither socat itself nor for dependent libraries.

	Now, to build an unstripped socat:		Now, build an unstripped socat:
	{{Commands\|		{{Commands\|
	$ nix-build -E 'with import <nixpkgs> {}; enableDebugging socat'		$ nix-build -E 'with import <nixpkgs> {}; enableDebugging socat'

imported>Symphorien: explain how to get debug info in gdb. maybe slightly too verbose.

2018-12-02T23:42:37Z

explain how to get debug info in gdb. maybe slightly too verbose.

New page

Nix packages rarely embed debugging symbols, and since the notion of "installing" a package is
somewhat complicated with nix, one cannot "just" install the <code>foo-dev</code> to magically get debug symbols for <code>foo</code>. Here are some explanations on how to get debug symbols with nix, and especially on NixOS.

By default, packages are stripped and all (most?) debug information is irrevocably lost. If you want to debug an application
using a library from such a package, there is little you can do to get debug symbols.

Two types of packages can provide debug symbols:
==== Unstripped packages ====
Let's take the example of <code>socat</code>.

If you install socat, then run
{{Commands|
$ gdb socat
Reading symbols from socat...(no debugging symbols found)...done.
(gdb) start
(gdb) info shared
From To Syms Read Shared Object Library
0x00007ffff7dd8f50 0x00007ffff7df5080 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/ld-linux-x86-64.so.2
0x00007ffff7bd2220 0x00007ffff7bd4fec Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/librt.so.1
0x00007ffff79cde80 0x00007ffff79ce705 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libutil.so.1
0x00007ffff779afa0 0x00007ffff77bb274 Yes (*) /nix/store/z2zhmrg6jcrn5iq2779mav0nnq4vm2q6-readline-6.3p08/lib/libreadline.so.6
0x00007ffff752b140 0x00007ffff7569c36 Yes (*) /nix/store/9kr8r78bwk12050ppywfbhg1vrsd6dp8-openssl-1.0.2p/lib/libssl.so.1.0.0
0x00007ffff717d300 0x00007ffff72b893c Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libc.so.6
0x00007ffff6d66200 0x00007ffff6eabb8f Yes (*) /nix/store/9kr8r78bwk12050ppywfbhg1vrsd6dp8-openssl-1.0.2p/lib/libcrypto.so.1.0.0
0x00007ffff6adbbd0 0x00007ffff6ae9641 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libpthread.so.0
0x00007ffff687fce0 0x00007ffff68b9768 Yes (*) /nix/store/s2n99784krxl91mfw3cnn9ylbb5fjvkx-ncurses-6.1/lib/libncursesw.so.6
0x00007ffff6663e60 0x00007ffff6664a9e Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libdl.so.2
(*): Shared library is missing debugging information.
}}
you see that you have debugging symbols for neither socat itself nor for dependent libraries.

Now, to build an unstripped socat:
{{Commands|
$ nix-build -E 'with import <nixpkgs> {}; enableDebugging socat'
}}
Let's retry with gdb:
{{Commands|<nowiki>
$ gdb result/bin/socat
Reading symbols from result/bin/socat...done.
(gdb) start
Temporary breakpoint 1, main (argc=1, argv=0x7fffffffbe38) at socat.c:84
84 socat.c: No such file or directory.
(gdb) info shared
From To Syms Read Shared Object Library
0x00007ffff7dd8f50 0x00007ffff7df5080 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/ld-linux-x86-64.so.2
0x00007ffff7bd2220 0x00007ffff7bd4fec Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/librt.so.1
0x00007ffff79cde80 0x00007ffff79ce705 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libutil.so.1
0x00007ffff779afa0 0x00007ffff77bb274 Yes (*) /nix/store/z2zhmrg6jcrn5iq2779mav0nnq4vm2q6-readline-6.3p08/lib/libreadline.so.6
0x00007ffff752b140 0x00007ffff7569c36 Yes (*) /nix/store/9kr8r78bwk12050ppywfbhg1vrsd6dp8-openssl-1.0.2p/lib/libssl.so.1.0.0
0x00007ffff717d300 0x00007ffff72b893c Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libc.so.6
0x00007ffff6d66200 0x00007ffff6eabb8f Yes (*) /nix/store/9kr8r78bwk12050ppywfbhg1vrsd6dp8-openssl-1.0.2p/lib/libcrypto.so.1.0.0
0x00007ffff6adbbd0 0x00007ffff6ae9641 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libpthread.so.0
0x00007ffff687fce0 0x00007ffff68b9768 Yes (*) /nix/store/s2n99784krxl91mfw3cnn9ylbb5fjvkx-ncurses-6.1/lib/libncursesw.so.6
0x00007ffff6663e60 0x00007ffff6664a9e Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libdl.so.2
(*): Shared library is missing debugging information.
</nowiki>}}
You have got debugging symbols for socat, but not its dependencies. Also, gdb complains that it did not find the source files of socat.
For source files:
* download the tarball: <code>nix-build "<nixpkgs>" -A socat.src</code>
* extract it: <code>tar xvf result</code>
* back in gdb:
{{Commands|<nowiki>
(gdb) dir /tmp/socat-1.7.3.2/
Source directories searched: /tmp/socat-1.7.3.2:$cdir:$cwd
(gdb) where
#0 main (argc=1, argv=0x7fffffffbe38) at socat.c:84
(gdb) l
warning: Source file is more recent than executable.
79 #endif
80
81 bool havelock;
82
83
84 int main(int argc, const char *argv[]) {
85 const char **arg1, *a;
86 char *mainwaitstring;
87 char buff[10];
88 double rto;
</nowiki>}}
Semi-victory !

To provide debug info for dependencies, we would have to recompile them all with <code>enableDebugging</code> which is time consuming and tedious. The only reasonable solution would be to ship debugging information by default, but it would waste a lot of disk space. This leads to the second type of packages.

==== Packages with a debug output ====
Some packages are built with <code>separateDebugInfo = true;</code>. The debug symbols will be stripped from the normal output(s) of the derivation, but instead of being discarded they will be put in a special <code>debug</code> output.
Since the library does not depend on this output, no disk space is wasted by default.

The openssl package is such a derivation. Imagine you are debugging a live socat and suddenly want debug symbols for
openssl. Previous gdb output tells us the version of openssl we are interested in is <code>/nix/store/9kr8r78bwk12050ppywfbhg1vrsd6dp8-openssl-1.0.2p</code>. We can get back to the original derivation:
{{Commands|
$ nix-store --query --deriver /nix/store/9kr8r78bwk12050ppywfbhg1vrsd6dp8-openssl-1.0.2p
/nix/store/i12c15d9rnz45as76s0nsa0nypl0fl6z-openssl-1.0.2p.drv
}}
Then we can get the store path for the debug output:
{{Commands|<nowiki>
$ nix show-derivation /nix/store/i12c15d9rnz45as76s0nsa0nypl0fl6z-openssl-1.0.2p.drv | jq '.[]|.outputs.debug.path'
"/nix/store/xd69daaly33m7zid6g31glwmml7lk93f-openssl-1.0.2p-debug"
</nowiki>}}
This store path is probably not yet on our disk, so let's download it:
{{Commands|
$ nix-store -r "/nix/store/xd69daaly33m7zid6g31glwmml7lk93f-openssl-1.0.2p-debug"
}}
And now we can tell gdb that debug symbols are in the <code>lib/debug</code> subdirectory with <code>set debug-file-directory</code>:
{{Commands|<nowiki>
$ gdb result/bin/socat
(gdb) set debug-file-directory /nix/store/xd69daaly33m7zid6g31glwmml7lk93f-openssl-1.0.2p-debug/lib/debug
(gdb) start
(gdb) info shared
From To Syms Read Shared Object Library
0x00007ffff7dd8f50 0x00007ffff7df5080 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/ld-linux-x86-64.so.2
0x00007ffff7bd2220 0x00007ffff7bd4fec Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/librt.so.1
0x00007ffff79cde80 0x00007ffff79ce705 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libutil.so.1
0x00007ffff779afa0 0x00007ffff77bb274 Yes (*) /nix/store/z2zhmrg6jcrn5iq2779mav0nnq4vm2q6-readline-6.3p08/lib/libreadline.so.6
0x00007ffff752b140 0x00007ffff7569c36 Yes /nix/store/9kr8r78bwk12050ppywfbhg1vrsd6dp8-openssl-1.0.2p/lib/libssl.so.1.0.0
0x00007ffff717d300 0x00007ffff72b893c Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libc.so.6
0x00007ffff6d66200 0x00007ffff6eabb8f Yes /nix/store/9kr8r78bwk12050ppywfbhg1vrsd6dp8-openssl-1.0.2p/lib/libcrypto.so.1.0.0
0x00007ffff6adbbd0 0x00007ffff6ae9641 Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libpthread.so.0
0x00007ffff687fce0 0x00007ffff68b9768 Yes (*) /nix/store/s2n99784krxl91mfw3cnn9ylbb5fjvkx-ncurses-6.1/lib/libncursesw.so.6
0x00007ffff6663e60 0x00007ffff6664a9e Yes (*) /nix/store/fg4yq8i8wd08xg3fy58l6q73cjy8hjr2-glibc-2.27/lib/libdl.so.2
(*): Shared library is missing debugging information.
</nowiki>}}
Victory!

Unfortunately, it seems you must issue <code>set debug-file-directory</code> before the library is loaded. If you already have typed <code>start</code> or if you have attached a live <code>socat</code> with <code>gdb -p</code>, <code>set debug-file-directory</code> won't have any effect. In this case you can export <code>NIX_DEBUG_INFO_DIRS=/nix/store/xd69daaly33m7zid6g31glwmml7lk93f-openssl-1.0.2p-debug/lib/debug</code> before launching gdb.

==== NixOS ====
By toggling <code>environment.enableDebugInfo</code> to 'true' in <code>/etc/nixos/configuration.nix</code>, all
separate debug info derivations in your <code>systemPackages</code> will have their debug output linked in <code>/run/current-system/sw/lib/debug/</code> and
will be automatically available to gdb. If a derivation you are interested in does not have separate debug info enabled, you
still have to override it with an overlay for example.