How to Cross-Build Debian/MIPS Kernel


I was trying to install Debian/MIPS on QEMU and found out that I need to build/update the kernel.  The existing instructions mostly talk about native build, which is painfully slow on QEMU.  I tried once and it took almost 10 hours!  There are some references to cross-build debian kernel and none applies straightforwardly.    I decided to write a blog on how I did it.

Prepare the host

  • My host is Ubuntu 18.04
  • I’m building 64bit MIPS little endian kernel for malta board
  • Need install a build related packages :
    • apt install -y build-essential linux-source bc kmod cpio flex cpio libncurses5-dev bison libssl-dev
  • Need to install crosscompile tools.  Fortunately we only need gcc and binutils for compiling kernel
    • apt install -y binutils-mips64-linux-gnuabi64 gcc-mips64-linux-gnuabi64

Set up the source

  • Download and unpack kernel source and config from debian site
    • cd download
    • wget
    • wget
  • Extract the kernel source from .deb file
    • dpkg -x download/linux-source-4.19_4.19.67-2+deb10u2_all.deb .
    • tar xf usr/src/linux-source-4.19.tar.xz
  • Copy and modify the kernel config as you see fit
    • dpkg -x download/linux-config-4.19_4.19.67-2+deb10u2_mips64el.deb .
    • unxz usr/src/linux-config-4.19/config.mips64el_none_5kc-malta.xz
    • patch -p0 -b < kconfig.patch
    • cp usr/src/linux-config-4.19/config.mips64el_none_5kc-malta linux-source-4.19/.config
  • Make deb packages for kernel
    • cd linux-source-4.19
    • make ARCH=mips CROSS_COMPILE=mips64-linux-gnuabi64- oldconfig
    • make ARCH=mips CROSS_COMPILE=mips64-linux-gnuabi64- KDEB_PKGVERSION=1 -j`nproc` bindeb-pkg

Download the source

Below the script file and kernel config patch would work together to execute the above steps automatically.