linux-kernel - How to deal with increased install size with `CONFIG_DEBUG_INFO

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Message-ID: <15bcb208-3ccb-4d99-853b-545626914373@molgen.mpg.de>
Date: Mon, 25 Aug 2025 17:42:05 +0200
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: How to deal with increased install size with
 `CONFIG_DEBUG_INFO_BTF=y`

Dear Linux folks,


Trying to get ptcpdump [1] running, I needed to build Linux with BTF 
symbols.

```
@@ -5985,11 +5986,22 @@
  #
  # Compile-time checks and compiler options
  #
+CONFIG_DEBUG_INFO=y
  CONFIG_AS_HAS_NON_CONST_ULEB128=y
-CONFIG_DEBUG_INFO_NONE=y
+# CONFIG_DEBUG_INFO_NONE is not set
  # CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT is not set
  # CONFIG_DEBUG_INFO_DWARF4 is not set
-# CONFIG_DEBUG_INFO_DWARF5 is not set
+CONFIG_DEBUG_INFO_DWARF5=y
+# CONFIG_DEBUG_INFO_REDUCED is not set
+CONFIG_DEBUG_INFO_COMPRESSED_NONE=y
+# CONFIG_DEBUG_INFO_COMPRESSED_ZLIB is not set
+# CONFIG_DEBUG_INFO_SPLIT is not set
+CONFIG_DEBUG_INFO_BTF=y
+CONFIG_PAHOLE_HAS_SPLIT_BTF=y
+CONFIG_PAHOLE_HAS_LANG_EXCLUDE=y
+CONFIG_DEBUG_INFO_BTF_MODULES=y
+# CONFIG_MODULE_ALLOW_BTF_MISMATCH is not set
+# CONFIG_GDB_SCRIPTS is not set
  CONFIG_FRAME_WARN=2048
  # CONFIG_STRIP_ASM_SYMS is not set
  # CONFIG_READABLE_ASM is not set
```

This increased the module size quite a bit:

     $ du -sh /lib/modules/6.12.4*
     128M        /lib/modules/6.12.40.mx64.484
     1.9G        /lib/modules/6.12.43.mx64.485

Searching the WWW, it was suggested to run `INSTALL_MOD_STRIP=1` [2], 
bringing it down to 137 MB:

     137M        /lib/modules/6.12.43.mx64.486

I was under the expression, that BTF symbols are small compared to the 
debug symbol types from the past. (Excuse my ignorance about the 
terminology and subject.) Is `INSTALL_MOD_STRIP=1` the “recommended” way 
to still use BPF/BTF on production systems.


Kind regards,

Paul


[1]: https://github.com/mozillazg/ptcpdump
[2]: 
https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/28218/diffs