See also:   https://lwn.net/Articles/743609/

don't expect network to work exactly the same

This "Linux" source code tree is specifically for building
a kernel that boots on my GnuBee-PC1.  Maybe it will work for you too.
It contains some hacks and extras.

To build and boot a kernel:

1/ get a MIPS cross compiler (unless you are going to build on the
   Gnubee itself).  See below if you don't have one.

2/ copy the script mkgnubee-initramfs.sh to your Gnubee with
   Debian installed, and run it.  It will create
   "gnubee-initramfs.tgz".  You might need to apt-get install busybox
   first.

3/ copy the gnubee-initramfs.tgz here and
     tar xvf gnubee-initramfs.tgz
   to place the contents here.

4/ Create a directory for storing the compiled result.  I use the subdir "O".
    When you see "O=O" below, replace by "O=the-directory-you-created".

5/ If cross-compiling,
   export ARCH=mips
   export CROSS_COMPILE= .... whatever

6/ make O=O gnubee1_defconfig

    the O/.config this creates knows where to find the initramfs
    to created earlier.

7/ make -j8 O=O

   you might want a different '-j' value, depending on how many
   CPU cores you have.

8/ make O=O INSTALL_MOD_PATH=`pwd`/initramfs modules_install

   This puts all the modules in the initramfs

9/ copy initramfs/lib/modules to your gnubee Debian install.
  Your Debian GNUBEE-ROOT filesystem can be on USB, the uSD card,
  or a SATA drive partition; all are now supported.

10/ make O=O uImage

11/ copy O/arch/mips/boot/uImage.bin to an USB drive as gnubee.bin.

12/ boot - wait - unplug usb - boot - enjoy.

13/ The gnubee.bin contains all the kernel modules, and
  normally will leave them in a tmpfs filesystem mounted on /lib/modules
  so you don't have to install them separately.  This is convenient, but
  is a waste of memory.  If you want to stay with this firmware it is
  best to copy the modules into your root filesystem.  Then the firmware
  will not keep a copy.  If you did this in step 9 above, you don't have
  to do anything else from the booted system.  Alternatively, you can:
    mkdir /tmp/modules
    mount --bind /lib/modules /tmp/modules
    umount -l /lib/modules
    cp -a /tmp/modules/. /lib/modules
    umount /tmp/modules


-------------------------------------------------------
If you don't have a cross compiler, this is how I got one.
I put all my git trees in /home/git.  You might put them elsewhere.


Install gmp mpfr mpc devel packages

cd /home/git
git clone git://sourceware.org/git/binutils-gdb.git
git clone git://gcc.gnu.org/git/gcc.git

cd binutils-gdb
git checkout binutils-2_29_1
mkdir MIPS
cd MIPS
../configure --target=mipsel-unknown-linux-gnu --prefix=/opt/cross
make
sudo make install

cd ../../gcc
git checkout gcc-7_2_0-release
mkdir MIPS
cd MIPS
../configure --target=mipsel-unknown-linux-gnu --prefix=/opt/cross \
  --enable-languages=c --without-headers \
  --with-gnu-ld --with-gnu-as \
  --disable-shared --disable-threads \
  --disable-libmudflap --disable-libgomp \
  --disable-libssp --disable-libquadmath \
  --disable-libatomic
make -j8
sudo make install

This will install the cross-tools in /opt/cross
You need to add /opt/cross/bin to your path.
e.g.
  export PATH=/opt/cross/bin:$PATH

To use the tools to compile Linux:

 export ARCH=mips CROSS_COMPILE=mipsel-unknown-linux-gnu-