Building on case-insensitive filesystems

[Dan Kegel <dank@kegel.com>]

$ ls {include/linux/netfilter_ipv4,net/ipv4/netfilter}/*.{h,c}
shows eight pairs of files whose names differ only in case.
For example:
$ more include/linux/netfilter_ipv4/ipt_{mark,MARK}.h
::::::::::::::
include/linux/netfilter_ipv4/ipt_mark.h
::::::::::::::
#ifndef _IPT_MARK_H
#define _IPT_MARK_H

struct ipt_mark_info {
     unsigned long mark, mask;
     u_int8_t invert;
};

#endif /*_IPT_MARK_H*/

::::::::::::::
include/linux/netfilter_ipv4/ipt_MARK.h
::::::::::::::
#ifndef _IPT_MARK_H_target
#define _IPT_MARK_H_target

struct ipt_mark_target_info {
         unsigned long mark;
};

#endif /*_IPT_MARK_H_target*/

Seems like ipt_mark_target.h might be a better name for
that latter file.  That would let developers who have
MacOSX or Windows laptops successfully unpack the
Linux source tree on their computers' case-insensitive filesystems.

I maintain http://kegel.com/crosstool, which is a script
that builds arbitrary combinations of gcc + {g,uc}libc + binutils + linux headers + target.
As a check on the resulting cross toolchains, I try building
a Linux kernel.  This works great in general, but on
operating systems with case-insensitive filesystems
(MacOSX, Cygwin), building the linux kernel understandably fails on these files.

Here's the patch I've been using to do a rename and fix Makefiles to match:
   http://www.kegel.com/crosstool/linux-2.6.8-netfilter-case-insensitive.patch
It renames the uppercase variants to add a _u suffix, but I would
gladly rework the patch to use a nicer suffix (like _target) if
that would help make the rename happen.

This is part of a larger effort to make life easier for
embedded Linux developers who are stuck developing on Windows
or Mac systems; see discussion at
http://marc.theaimsgroup.com/?l=linux-kernel&m=109713211417106&w=2
(Summary: Sam Ravnborg is helping; Russel King is skeptical.)
- Dan

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