Re: Mac-on-Linux

On Fri, May 21, 1999 at 09:35:21PM -0500, David A. Gatwood wrote:

Quick question: what is the nature of the kernel support for mac-on-linux? 
Some folks in the MkLinux camp have been discussing writing equivalent
2.0.xx kernel code that works through mach.  I know that it will likely
need to be able to map the ROMs into user space.  I also suspect that
handling code (which could be very messy, but we'll cross that bridge when
we get to it) and possibly the memory management code.  Beyond that, what
other hurdles are there?

The Mac-on-Linux kernel support code has in principle the following 
tasks:

  - Emulate privileged instructions.
  - Handle the MMU (maps ROM, RAM etc.)

The implementation is primarily based upon hooks in the
low-level exception handlers. Besides this, the interaction
with the kernel has been kept at a minimum.

I believe the exception hooks must be put into the
mach kernel - possibly it is easiest to put all code 
there.

/Samuel


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On Sat, 22 May 1999, Samuel Rydh wrote:

The Mac-on-Linux kernel support code has in principle the following 
tasks:

  - Emulate privileged instructions.
  - Handle the MMU (maps ROM, RAM etc.)

The implementation is primarily based upon hooks in the
low-level exception handlers. Besides this, the interaction
with the kernel has been kept at a minimum.

I believe the exception hooks must be put into the
mach kernel - possibly it is easiest to put all code 
there.

There would be advantages and disadvantages.  Speed-wise, it'd be great if
it were all in mach and if the mac-on-linux binary were mach aware,
detecting Mach's presense, and using direct calls into Mach. 
Simplicity-wise, we could stick an abstraction layer in there in the linux
server so that it mostly looked the same to mac-on-linux whether it was
running on LinuxPPC or MkLinux.  Not sure which would end up being the
most advantageous, but it's probably a moot point until the Mach handling
changes are made.  :-)


Later,
David

David A. Gatwood                         Visit globegate's internet
dgatwood@globegate.utm.edu                  talker, Deep Space 36
http://globegate.utm.edu                telnet globegate.utm.edu:9624


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