liminix

commit c80e7d33ed25d785b12950f10dfb7729b37023f8
parent 8e36690ae2ad7439188bc2b2319da48e6d723faf
Author: Peter Collingbourne <peter@pcc.me.uk>
Date:   Sat, 16 May 2026 20:18:05 -0700

Stop unnecessarily removing sections from the kernel binary

We just need -S here which removes non-SHF_ALLOC sections. SHF_ALLOC
sections are generally required to be in the kernel image, and can't be
removed (in the sense of shrinking the binary) by a tool like objcopy
because that would alter the section layout which is fixed by the
linker. objcopy was "removing" these sections by replacing them with
zeros, so this wasn't reducing the size of the kernel anyway.

In particular, this command was removing the .notes section containing
the build ID which is readable from userspace via /sys/kernel/notes and
may be used for symbolization on the host.

Diffstat:
M
modules/outputs/tftpboot.nix
 | 
2
+-
M
pkgs/kernel/uimage.nix
 | 
2
+-

2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/modules/outputs/tftpboot.nix b/modules/outputs/tftpboot.nix
@@ -85,7 +85,7 @@ in
           cmdline = concatStringsSep " " config.boot.commandLine;
           objcopy = "${pkgs.stdenv.cc.bintools.targetPrefix}objcopy";
           stripAndZip = ''
-            ${objcopy} -O binary -R .reginfo -R .notes -R .note -R .comment -R .mdebug -R .note.gnu.build-id -S vmlinux.elf vmlinux.bin
+            ${objcopy} -O binary -S vmlinux.elf vmlinux.bin
             rm -f vmlinux.bin.lzma ; lzma -k -z  vmlinux.bin
           '';
         in
diff --git a/pkgs/kernel/uimage.nix b/pkgs/kernel/uimage.nix
@@ -9,7 +9,7 @@ let
   objcopy = "${stdenv.cc.bintools.targetPrefix}objcopy";
   arch = stdenv.hostPlatform.linuxArch;
   stripAndZip = ''
-    ${objcopy} -O binary -R .reginfo -R .notes -R .note -R .comment -R .mdebug -R .note.gnu.build-id -S vmlinux.elf vmlinux.bin
+    ${objcopy} -O binary -S vmlinux.elf vmlinux.bin
     rm -f vmlinux.bin.lzma ; lzma -k -z  vmlinux.bin
   '';
 in