Changes from MK83 to the UK02-freeze branch

This page contains a brief, high-level outline of the major changes made so far in the "UK02" branch, with respect to CMU's MK83 kernel which it is based on. For a more detailed list of what changed and when, see the ChangeLog files in the source trees.

Build environment: Ripped out the old ODE build environment and replaced it with an easier-to-use GNU-style build environment.
New i386 bootstrap system: Replaced the old kludgy microkernel boot loading mechanism, in which the server bootstrap code was loaded in the kernel's BSS area, with a newer, bigger, more powerful, more complex, and even kludgier mechanism. :-)
Public Includes: Previously Mach exported some public header files that were not under the `mach/' subdirectory, and tended to conflict with identically named header files that Unix C libraries and servers wanted to supply. These have now been moved under the `mach/' subdirectory, to help to get Mach "out of the way" of other higher-level software, and make it less Unix-specific (or, at least, less CMU-UX-single-server specific). Personalities that want to use the Mach-supplied versions of these header files can simply create stub files that cross-include the appropriate Mach files.
Specific changes:
- `sys/': Mach no longer has a global `sys' include directory. The needed files in it have been moved to the `mach' directory or to private directories. The `sys' directory should be left available for higher-level OS software. (Already the Hurd was having to kludge around its presence; see below about how to compile it with this version of Mach.)
- `machine/': Mach no longer exports a global `machine' or `i386' include directory. Again, these are the domain of higher-level software and should not be touched by Mach. There is still a `mach/machine/' subdirectory for publicly exported machine-dependent Mach header files.
- `cthreads.h': Has been moved to `mach/cthreads.h', because Mach's cthreads library is really only the "default" threads implementation. Higher-level OS personalities, such as the Hurd, need to be able to supply a different version if necessary. If a personality just wants to use Mach's default cthreads library, it can create a `cthreads.h' that simply cross-includes `mach/cthreads.h'.
MACH_IPC_COMPAT: Another change that might cause incompatibilities is that MACH_IPC_COMPAT is now not defined by default. If it breaks anything, you can turn it on by saying `export DEFS=-DMACH_IPC_COMPAT' before running the configure script. If this breaks a lot of important old Mach software (what Mach software? :-) ), I may turn it back on by default.
htg_vm_map: I don't support the htg_vm_map kludge in libmach, which has no business supporting special obscure presentations for higher-level software such as the emulator (which is what this kludge is for). Let the emulator create its own client presentation of mach.defs with vm_map() renamed. (If you want to know what a presentation is, read our paper on Using Annotated Interface Definitions to Optimize RPC .
Coding Style Changes: I've "set in motion" a few minor coding style changes in order to make the kernel source code more flexible and easier to work with.