NetBSD/sys/arch/amiga/doc/README.68040

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This version of NetBSD now includes support for the 68040. This version
should support both the 68030 and 68040 processors with a single kernel.
The config option FPSP will include the full Floating Point Support
Package to provide emulation of the floating point instructions not
implemented by the 68040. If the FPSP option is not used, then a
dummy file is included that will cause a panic if any FPSP routine
is called. This allows building a smaller kernel specifically for
the 68030.
The FPSP is provided as an object file. The FPSP was ported to gas by
Eric Norum (eric@skatter.usask.ca) and is available by anonymous ftp from:
ftp.usask.ca /pub/software/fpsp/fpsp_gas.tar.gz
Note: Motorola still holds the title and all rights to the FPSP.
Support for the Progressive Peripherals Incorporated Zeus SCSI interface
is also included. If the configuration file does not include support for
the A3000/A2091/GVP11 drivers, then including the "zeusscsi" driver will
configure the driver to use the sd (disk) and st (tape) devices. If any
of the A3000/A2091/GVP11 drivers are configured, then including the zeusscsi
driver will be configured to use a second set of scsi devices: rz (disk)
and tz (tape). The rz and tz devices have different major device numbers:
rz - 5 = block, 9 = character
tz - 8 = block, 23 = character
WARNING: since the PPI Zeus SCSI uses the level 6 interrupt, the kernel
must be compiled with the splbio() macro defined as spl6(). If not,
then then random kernel hangs will occur. One bad side effect of changing
splbio() is that it will also block the clock interrupts, which can
result in incorrect timing. The 53C710 driver (siop.c) also includes
support the the CSA Magnum 40, but this has not been tested yet.
The 68040 MMU implementation is not optimal at this time. It was added
in a manner to fit in with the current 68030 MMU setup without needing
to completely rewrite the MMU routines. The existing 68030 MMU layout
was implemented using a two level table: a segment table, and a page
table. The 68040 MMU can only use a three level table. To simulate a
two level table, the top level descriptor table is set up and the full
level 2 descriptor table is allocated and used as the "segment" table.
This results in 9 pages, or 72K bytes, being allocated for the initial
page table for each process.
The reboot command does not work for some reason. It appears to do the
reset instruction, but doesn't seem to do anything after that.
Michael Hitch