# How To build a XEN Domain-0 linuxkernel with SKAS & sysemu
# to run UML and XEN on the same host.
#
# Nils Toedtmann <xen-uml@nils.toedtmann.net>
# 
# 2005-02-28


# Disclaimer: i have NO clue what the hell i am doing here. 
# I do not know C nor assembler nor any linux kernel internals.
# I just stired up some patches until the result compiled ...
# At least some binaries (eg. /bin/ls under FC3) will segfault
# within UMLs guests running on such a hostkernel. So if it 
# eats your data - don't blame me ...


# get sources
mkdir archive
cd    archive/
wget  http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.10.tar.bz2
wget  http://www.cl.cam.ac.uk/Research/SRG/netos/xen/downloads/xen-2.0.4-src.tgz
wget  http://www.user-mode-linux.org/~blaisorblade/patches/skas3-2.6/host-skas3-2.6.10-v7.patch 
cd    ..


# make self-contained Xen kernel patch
tar   xzf archive/xen-2.0.4-src.tgz
tar   xjf archive/linux-2.6.10.tar.bz2
cp    -al linux-2.6.10 linux-2.6.10-xen-2.0.4
cd    xen-2.0/linux-2.6.10-xen-sparse/
./mkbuildtree ../../linux-2.6.10-xen-2.0.4/  # produces a lot of symlinks to the xen-tree :-(
cd    ../..
echo  "-xen-2.0.4" > linux-2.6.10-xen-2.0.4/localversion-xen
diff  -Naur linux-2.6.10 linux-2.6.10-xen-2.0.4 > archive/linux-2.6.10-xen-2.0.4.patch
rm    -fR   linux-2.6.10-xen-2.0.4 xen-2.0


# split up SKAS patch using "patchutils"
mkdir archive/host-skas3-2.6.10-v7
cd    archive/host-skas3-2.6.10-v7
splitdiff -dap1 ../host-skas3-2.6.10-v7.patch
cd    ../..


# make a new kernel-tree combining all patches
cp    -al linux-2.6.10 linux-2.6.10-skas3-v7-xen-2.0.4
cd    linux-2.6.10-skas3-v7-xen-2.0.4/

patch -p1 < ../archive/linux-2.6.10-xen-2.0.4.patch
patch -p1 < ../archive/host-skas3-2.6.10-v7.patch

patch arch/xen/i386/Kconfig                  < ../archive/host-skas3-2.6.10-v7/arch_i386_Kconfig 
patch arch/xen/i386/kernel/entry.S           < ../archive/host-skas3-2.6.10-v7/arch_i386_kernel_entry.S 
patch arch/xen/i386/kernel/ldt.c             < ../archive/host-skas3-2.6.10-v7/arch_i386_kernel_ldt.c 
patch include/asm-xen/asm-i386/desc.h        < ../archive/host-skas3-2.6.10-v7/include_asm-i386_desc.h 
patch include/asm-xen/asm-i386/mmu_context.h < ../archive/host-skas3-2.6.10-v7/include_asm-i386_mmu_context.h 
patch include/asm-xen/asm-i386/ptrace.h      < ../archive/host-skas3-2.6.10-v7/include_asm-i386_ptrace.h 
cd ..


# make a combined patch for later use
diff  -Naur linux-2.6.10 linux-2.6.10-skas3-v7-xen-2.0.4 | bzip2 -c > archive/linux-2.6.10-skas3-v7-xen-2.0.4.patch.bz2


# this combo tree actually compiles (!):
mkdir install
cd linux-2.6.10-skas3-v7-xen-2.0.4/
cp arch/xen/configs/xen0_defconfig .config
ARCH=xen ; INSTALL_PATH=../install ; INSTALL_MOD_PATH=../install 
export ARCH INSTALL_PATH INSTALL_MOD_PATH
make oldconfig
  /proc/mm support (PROC_MM) [Y/n] (NEW) y
make modules 
make modules_install
make install


# done. Copy the stuff from ${INSTALL_PATH} to the right places and boot it.