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.
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.)
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.
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'.
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.
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.