I am attempting to build a custom kernel for the i386 architecture and I have been trying to target the kernel at the 586 processor.

I have a kernel configuration, which defines CONFIG_M586=y, in the kernel source tree: ./arch/x86/configs/i386_vyos_defconfig

I then run make i386_vyos_defconfig followed by make-kpkg kernel_image. However at some point during the build process the .config file is updated to set CONFIG_M686=y instead.

I have attempted to set '--subarch i586' but it doesn't seem to help.

What is going on and how I configure it to target 586 instead, or not update the .config file?

My Kernel configuration is here: https://gist.github.com/njh/d6191ee130620ccd190e9273864775bd

I am using kernel-package version 13.014+nmu1 on Debian 8 (jessie).

  • If you are doing it because you need CPU support, have a look at Antix – Rui F Ribeiro Feb 3 at 18:42
  • I am going to it add i386 support to VyOS 1.2.0 (which is based on Debian Jessie) – njh Feb 3 at 19:14

I have not worked out how to fix it but I am now confident that my issue is a bug, not a feature of Debian kernel building.

I traced the kernel change back to the following chain of events:

  1. Run: make-kpkg kernel_image
  2. This executes make -f /usr/share/kernel-package/ruleset/minimal.mk debian
  3. Which ends uo triggering the target: debian/stamp/pre-build-common
  4. Which depends on the target: debian/stamp/conf/vars
  5. Which executes: make -f ./debian/ruleset/kernel_version.mk debian_conf_var
  6. kernel_version.mk includes the main Linux kernel Makefile
  7. For some reason this causes the Linux Makefile to run make syncconfig - I don't think it is supposed to

As far as I understand from reading an article about Kconfig/kbuild, the syncconfig target is just supposed to take the current configuration and generate some derived files from it. But for some reason it is changing my .config file too.

I think I have been far enough down this rabbit hole - time to escape.

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