The Hurd's pfinet server is based on networking code taken from
the Linux kernel sources, initially version 2.2.12 of Linux.
The subset of the Linux kernel sources used for pfinet is kept
in the linux-src subdirectory.

This file describes the procedures for tracking new Linux kernel versions
and updating the Linux networking code in the Hurd CVS repository.

The verbatim Linux kernel sources are kept on a vendor branch in CVS.  To
simplify the process of importing and merging new versions, I have mostly
imported whole subdirectories of the linux source tree rather than just the
precise subset of files we are actually using.  However, for the arch/*/lib
and include/asm-* subdirectories I have taken just the checksum files (the
only thing we use from the machine-dependent Linux code); and I have
removed the extraneous whole subdirectories within the include/linux and
include/net directories.  It is my intention to leave the remaining
extraneous files in the CVS repository, but to include in the distributions
only the files we are actually using (they will be listed in the Makefile).
They could also be left on the vendor branch and removed from the trunk, but
I think that would have more disadvantages than advantages.

The initial import was done with the following commands.  It is crucial to
use `-I !' in the `cvs import' command because of the directory
linux-src/net/core/ ("core" is in CVS's default list of names to ignore).

mkdir import-tmp
cd import-tmp
bunzip2 < linux-2.2.12.tar.bz2 | tar xf - linux/{'arch/*/lib/*checksum*','include/asm-*/checksum.h',include/{linux,net},net/{core,ipv4,ethernet}}
cd linux
rm -rf include/{net,linux}/*/
cvs -d `cat ../../CVS/Root` import -I ! -ko -m "Import of Linux 2.2.12 subset (ipv4 stack and related)" hurd/pfinet/linux-src Linux Linux_2_2_12

It should work to repeat the same procedure with later versions to upgrade
the `Linux' vendor branch.  Please import only verbatim official Linux
kernel sources, and stick to the tag name schema.  If you don't already
know how to merge the new vendor release into the trunk and finish the
upgrade, then you probably should not be doing this anyway.

On the main branch, only a few files within the linux-src tree are
modified, and those only lightly (the changes are described in ChangeLog).
Linux header files that are heavily modified or wholly replaced for use in
pfinet go into the glue-include/ subdirectory instead of modifying
linux-src files in place.  Whole C source files can just be replaced with
new files in the top-level pfinet source directory.  When modifications to
a file in linux-src are justified, the modifications should always be
conditionalized by #ifdef _HURD_.


	-- Roland McGrath <roland@gnu.org>	2000-02-03