[MiNT] Questions about 68040

["Konrad Kokoszkiewicz" <draco@obta.uw.edu.pl>]

Hello!

I am trying to write the 68040 version of the exception handler I've
recently added to MiNT (see freemint/sys/arch/check_exc.c), but the 68040
manual seems really puzzling to me. The appropriate section of it (Exception
processing - 8.4.6.7. Access error stack frame return from exception) speaks
all of pending write-backs, but the information on how to complete a READ
cycle seems to be missing.

An example: a program reads 0x05a0 in user mode (size = long, destination:
d0), bus error occurs. Nevertheless, say, I want the bus error handler to
simulate the read transparently to the user program (i.e. load the contents
of 0x05a0 to the d0 and resume). What the bus error handler is now supposed
to do to complete the read?

On 68030 this is easy, because the bus error stack frame provides a field
named "data input buffer", which is to be updated and the processor loads
this data into its viscera on RTE, and then processes further (e.g.
transfers to d0) automagically.

How do I do the same on 68040?

Help greatly appreciated.

--
CVV
Konrad M.Kokoszkiewicz, http://draco.atari.org

** Ea natura multitudinis est,
** aut seruit humiliter, aut superbe dominatur.
** Taka to już natura pospólstwa, albo służalczo się płaszczy,
** albo bezczelnie się panoszy. (Liwiusz XXIV, 25).