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SetCPU.txt
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1990-07-01
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SetCPU V1.60
by Dave Haynie
June 15, 1990
SetCPU V1.60 is a program designed for identification and
modification of system parameters roughly related to different versions
of the Motorola 68000 family processors. The program will identify the
various types of processors and coprocessors in any 680x0 system. It also
makes an attempt to correctly identify an incorrectly designed but still
possibly functional 68020 system, several of which are known to exist as
Amiga coprocessor boards. It contains MMU code to locate kernel ROM in
write protected 32 bit ROM.
In any case, the syntax of the program is given as follows:
SetCPU [INST|DATA] [[NO]CACHE|[NO]BURST] [CONFIG n] [BITS n] [TRAP n]
[KICKROM path|dfN: [DELAY n] [KEEPEXEC]] [CARDROM path] [VERBOSE]
[[NO]FASTROM [path] [KEYPATCH n] [HEAD] [NOSTACK]] [ROMBOOT]
[CHECK 680x0|68851|6888x|MMU|FPU|MMUON|MMUROM|MMUALIEN]
where "[]" indicates an optional parameter, "|" indicates a choice of
parameters. Typing "SetCPU ?" will retrieve this same syntax diagram.
Typing SetCPU alone will result in the SYSTEM configuration being
send to the console, my current system returns this:
SYSTEM: 68030 68882 FASTROM (INST: CACHE NOBURST) (DATA: CACHE NOBURST)
This indicates I have a 68030/68882 system, I've previously installed the
FASTROM translation, and both caches are turned on. Issuing the command
"SetCPU FASTOM CACHE" would recreate such a setup. Note that any parameters
that don't make sense to the real system configuration, such as asking to
modify the data cache on a 68020 system or install the FASTROM translation
on a 68000 system are just ignored.
[0] CHANGES
Since the V1.50 release of SetCPU, the following changes have been
made to the SetCPU program:
- FASTROM now supports loading of a ROM image file.
- The patch manager has been removed, except for the KEYPATCH
option.
- ROMs beyond 256K are now supported, from both file and special
KickStart disk.
- ROM images are supported assembled for various memory locations,
so that Commodore's developer files assembled at $00F00000, for
example, will work. SetCPU determines the size, base, and
jump address of a ROM independently.
- ExecBase can be erased on KICKROM resets to prevent Chip RAM
sizing problems and other OS switching errors.
- A programmable KICKROM DELAY option allows KICKROM to work on
better on some machines with extremely slow 8520 startup times.
- Caching for any Bridge Card memory will always be disabled.
- The system stack, if found in Chip memory, is relocated to Fast
memory for FASTROM translations.
- Some 2.0 functions are activated when run under the 2.0 OS, so
that most if not all of the basic SetCPU functions operate
properly.
- The MMU code is intelligent enough to avoid trashing an MMU setup
not generated by SetCPU.
[1] DISTRIBUTION
This program is placed in the public domain, and may be used or
distributed as you like.
[2] CPU IDENTIFICATION
There are two basic types of functions performed by SetCPU. The
first of these is CPU system identification and cache control. SetCPU will
tell about the type of CPU setup in your machine, which consists of the CPU
itself and sometimes FPU or MMU coprocessors. If the CPU supports caches,
SetCPU will let you switch these caches, and associated cache line burst mode,
on and off. Finally, SetCPU can be used in a Startup-Sequence or other script
to make decisions based on the system that's running. This is quite useful
with accelerator cards like the Commodore A2620 that let you boot the machine
with either 68020 or 68000 in charge. The individual CPU group commands are
given below in detail:
[NO]CACHE
This command will switch on or off 68020 and 68030 caches. If not
qualified, it'll act on both instruction and data caches of the 68030.
[NO]BURST
This command will switch on or off the burst cache line fill request
of the 68030. If not qualified, it'll act on both instruction and
data caches.
INST
This qualifies a CACHE or BURST operation to restrict its application
to the instruction cache only.
DATA
This qualifies a CACHE or BURST operation to restrict its application
to the data cache only.
CHECK
This option lets you check for the existence of a particular CPU
system component in a script. It works like this:
SetCPU CHECK 68020
If WARN
echo "No 68020 here!"
Else
echo "Sho nuff got a 68020 here!"
Endif
The arguments to CHECK can be any of:
68000 Matches the obvious
68010 "
68020 "
68030 "
68040 "
68851 "
68881 "
68882 "
FPU Matches 68881, 68882, or 68040
MMU Matches 68851, 68030, or 68040
MMUON Matches any case in which the MMU is enabled
MMUROM Matches an active SetCPU ROM translation
MMUALIEN Matches any MMU setup no created by SetCPU
If any cache parameter doesn't apply to the system in use, it'll just be
ignored. Use the data cache and all burst modes with caution. Some
68030 systems aren't designed to correctly support the data cache, so
switching it on may cause an instant system crash. Even on systems that
correctly support the 68030 data cache, some device drivers, especially
those for DMA devices, may not work properly with the data cache enabled.
You may wish to check with your system vendors to make sure before using
the data cache in your standard system setup. The Commodore A2091's device
driver does correctly support data caching. However, the use of the data
cache is not recommended without an MMU setup, such as FASTROM or one of
the KICK setups, invoked. The Amiga OS uses memory that's the same in
both Supervisor and User modes of the 680x0. This requires the setting
of the 68030's Write Allocate bit for safe operation, and SetCPU will
always insure that Write Allocate is set. However, this mode causes the
data cache to be updated on longword writes even for locations that are
driven noncacheable in hardware. So data caching without a proper MMU
setup can cause problems with some I/O devices. With the MMU setup,
SetCPU will map the standard Amiga I/O regions as noncachable.
SetCPU may report a "FPU Logic Error" on certain 68020 systems.
This is indicating a hardware problem with that board's floating point
coprocessor decoding, which results in the FPU responding to the MMU
addresses as well as its own. SetCPU knows how to handle such a board,
but future software using the MMU may not, so it's a good idea to report
this problem to the board vendor for repair.
[3] ROM TRANSLATIONS
The second thing that SetCPU V1.60 manages are ROM translations.
Using the MMU on systems so equipped, it can locate the Kernel ROM in the
much faster 32 bit wide memory provided on many 32 bit systems. It can
also boot a ROM based system with an alternate version of KickStart.
Most of the options here relate to MMU translation setup and various
modifications of the basic translation premise.
As of this release, SetCPU's MMU configurations will support
memory outside of the 68000's 24 bit address space, when it is present.
Such memory will be automatically recognized and supported by SetCPU if
it is linked into the free memory lists when SetCPU builds its FASTROM
or KICKROM. Alternatively, the number of significant bits of address
in the system can be specified by the BITS command, and SetCPU will
build the appropriate MMU table for such a system.
Another feature of this release is support for ROM images of either
256K or 512K in size. KickROMs may be assembled for locations other than the
$00FC0000 or $00F80000 base used by physical systems. SetCPU will compute
the size, base address, and start address for any KickROM image. ROM
images can now be loaded from disk for FASTROM translations as well as
KICKROM translations, though a FASTROM image must be the same KickStart
release as the current ROM in the system. This facility's main purpose is
to support loading of patched ROMs with the necessity of rebooting via
KICKROM. As a result of this, the only patch now done by SetCPU itself is
the optional KEYPATCH, which may be required for proper operation of the
accelerated ROM code on some systems.
[NO]FASTROM
This activates the FASTROM translation on or off an MMU equipped
system. When switching on, it first allocates at least 256K of
memory for the ROM image, then at least 512 bytes of memory for the
MMU table. It copies the ROM into the image area, then applies the
translation by pointing the MMU at the table and activating it. The
NOFASTROM option will switch off the MMU and reclaim the memory used
for the ROM image and MMU table. If any other program set up the MMU
for something, invoking this option could be a very bad thing to do.
In general, until there's some level of OS support for the MMU in
Amiga systems, you're really safe using only one MMU tool at a time.
If you have an A2620 or A2630 system, this option will always get 32
bit memory for you; if not, you'll have to make sure that your 32 bit
memory is the first MEMF_FAST memory in the memory list for it to be
used for the ROM image. Also, that ROM image will be allocated as far
back on that memory list as possible unless the "HEAD" option is
specified. The SetCPU "SYSTEM" line will report this setup as a
"FASTROM" setup.
Suboptions are:
file
Specifying a file with a valid ROM image will load that ROM
image instead of the system's physical ROM image. The one
restriction is that the disk-loaded ROM image must be the
same ROM revision as the current system ROM. If they aren't
the same revision, the KICKROM option can be used instead,
but that'll require a reboot. This option can be used to
load a patched version of the current ROM without reboot in
most cases.
KEYPATCH n
This will patch the keyboard scanning routine for machines
that have Cherry keyboards (small function keys). The "n"
parameter allows a variable delay between 1 and 100 to be
specified; the delay depends on the keyboard, but should
be pretty independent of CPU speed.
NOSTACK
This will prevent the attempted translation of supervisor
stack into 32 bit memory. By default, such translation will
be done if the supervisor stack is found in Chip memory.
CARDROM path
When used in conjunction with the FASTROM option, this allows ROMs
from expansion cards to be located in fast memory as well. The
path should reference a file containing lists of expansion cards
that should be translated if found. It's necessary to read this
from a user-defined file, rather than from the expansion environment
itself, since an expansion device's ROM could be located close to
that device's registers; there's no way for SetCPU to know it's
safe to translate a card ROM image unless you tell it. On my system
I read a file called CardROMList, which currently contains the single
line:
0x202 0x01 0x10000 0x8000 0x4000 CBM_2090A_Disk_Controller
All the numbers given are in C language hex format. The parameters
are, in order, the device's manufacturer code, product code, the
device's size (in bytes), the ROM's offset from the configured board's
base address (in bytes), and the size of the ROM area to be
translated (in bytes). The final item is text string to identify
the device; this'll be displayed by the VERBOSE option if the ROM
translation does in fact take place. The "_" characters in the
name will be translated to " " characters. Note that the CardROM
translations are currently based on 16K chunks, and SetCPU will
ignore requests for translations of less than 16K, and round down to
16K boundaries for larger translation requests.
HEAD
This option causes the SetCPU memory allocator to attempt memory
allocation for its translated objects from the start of 32 bit
memory instead from the end, as it usually does. Allocation from
the end usually results in less fragmentation than from the start
(due to the alignment restrictions of MMU objects), though this
option is useful when dealing with merged memory lists. It is
ignored when the ROM image and tables are in chip/$00C00000 memory.
KICKROM path|dfN:
The KickROM option allows the system to be restarted with an
alternate ROM image. This can be from a KickStart disk in a
specified floppy drive, or from a given file name. If the
ROM image is accessible, this command will cause the system to
be immediately rebooted into the new OS. Note that pre-1.3
versions of the Amiga operating system will probably have some
trouble with expansion cards, especially autoboot cards. For
that reason there's the CONFIG 0 option, which is explained
later.
The KICKROM command will reboot the machine with the new OS, but
that ROM image will be physically located in either memory at
$00C00000, if it's available, otherwise it'll use Chip memory. Once
the new OS has started up, issuing either "SetCPU FASTROM ..." or
"SetCPU KICKROM..." will cause that image to be moved into fast
memory, and the slow memory will be given back to the system. The
SetCPU "SYSTEM" line will report a 16 bit KICKROM image as a
"SLOWKICK", and a 32 bit KICKROM image as a "FASTKICK". A machine
running from a SLOWKICK kernel can't be re-KICKROMed, but can be
from a FASTKICK kernel.
Suboptions are:
DELAY n
This option sets the delay after reset before any code is
run. The parameter may be set from 0 to 100, where 0 sets
no delay. The default value is 10, which sets the delay
value used in SetCPU V1.50. The need for a delay depends
on the machine you're on. If your machine hangs after
SetCPU loads KickStart, there's a real good chance that
you need a longer delay.
KEEPEXEC
Normally, KICKROM will clear the ExecBase pointer, to cause a
the new version of the ROM to be rebuild from a cold boot
condition. This option prevents that clearing action.
CONFIG n
This option controls if and how expansion devices are recognized on
a KICKROM boot. At the default configuration level, level 2, the
expansion cards are left alone, allowing the new Kernel to try and
configure them. Since some older operating system will choke on
autoboot devices, this option will allow suppression of them for the
rebooting process. When requesting a KICKROM boot, a CONFIG level
of 0 or 1 will prevent the devices from being recoginzed.
Once rebooted in the new OS, moving from a SLOW to a FAST Kick image,
as described above, the CONFIG status will be honored. If the
devices weren't suppressed, nothing special happens. If they were,
they'll stay suppressed, and you very likely won't have the memory
to support a FAST Kick image. Specifying a CONFIG level of 2 at
this point will attempt to configure the devices without autobooting.
At level 1, the devices will be made visable to the system again,
but nothing will be done with them.
As of the latest release, CONFIG 0 appears to be required with the
1.2 operating system, at least if there's any autoboot device, even if
you're attempting to move from a slow to fast kick image. The next
release will attempt to allow 1.2 to configure non-autobooting devices
at this point.
TRAP n
This option controls the level of error trapping handled for
you by the SetCPU system. The numeric parameter is actually
optional for compatibility with SetCPU V1.4. If no TRAP is
specified, the default level 2 is enacted. If the TRAP command is
given without a parameter, trap level 0 will be setup.
Trap level 0 causes the MMU to look at all 32 bits of address;
access to any memory outside of the 24 bit space will result
in an exception, which if unhandled, results in a GURU 2. Trap
level 1 will set up the MMU to only look at 24 bits of address space.
Trap level 2 works like level 1, but additionally sets up a trap
handler for the Bus Error exception (which usually surfaces as a
GURU #2). For normal operation (eg, running other people's code),
Trap level 2 is probably what you want. For final testing of your
own code, levels 0 or 1 can catch things which would go unnoticed
on a 68000 machine, such as writing to ROM space or out of the 24
bit address space.
The exception handler used for level 2 trapping catches things like
writes to protected areas of memory. It just tells the bus machine
not to complete the write, and signals no error. There's a slight
chance that this won't be enough repair for a program doing something
really outlandish -- at that point, running at level 1 will let the
GURU happen, which might help if you're debugging your own code.
Other that that, there's probably nothing you can do to get such a
program working with the MMU turned on, other than having it fixed.
The other thing to consider is that this exception handler could
conflict with another system-level handler installed by a GOMF-like
program. That shouldn't cause a big problem, since you'll the one
that was installed later, both of which presumably trap the error,
but it's something to be aware of.
Under V1.3 and earlier releases, a DOS bug can cause invalid accesses,
which cause the exception, when running the EndCLI or NewCLI/NewShell
programs; running at level 1 or 2 will avoid gurus with these commands.
BITS n
This option forces the MMU table for KICKROM or FASTROM to be built
to support a specific number of bits, regardless of the actual bits
apparently used by the system. Valid significant bits range from 24
through 32.
ROMBOOT
This option forces a reset to physical ROM without hanging the system,
even when the MMU is active.
VERBOSE
This option more fully describes the system translations.
[4] ROM FILE FORMATS
The 256K KickStart disk the KICKROM option will look for is the
standard Commodore KickStart format, which is a standard format floppy
with the work "KICK" at the start of the disk, followed by 512 blocks of
512 bytes each, a plain dump of the ROM image. 512K KickStart disks
look just the same, only, of course, with 512K of ROM. The KickStart
loader will actually check the first 32 blocks of disk for the start of
ROM.
The size of the KickStart image is determined by the first longword
of the file. Optionally, disk files can contain two extra longwords at the
beginning of the file, the first being a $00000000, second the expected
size of the ROM image. That expected size will be compared with the expected
based on the first longword in the ROM image and the actual length of the
loaded file, in the case of a disk file rather than a KickStart. The base
address and starting address are determined from the ROM image, and SetCPU
will attempt to use them. Some ROM images can cause a conflict with other
system resources.
[5] CREDITS
While this program is an entirely original work, nothing happens in
vaccuum, this one included. I'd like to mention folks who, directly or
indirectly, helped make this thing happen, by providing example MMU code,
suggestions, and incentives. These folks include Neil Katin, Jez San,
GVP Inc., Dale Luck, Bryce Nesbitt, Andy Finkel, and the other Commodore-Amiga
software people, and the Commodore-Amiga Technical Support folks.
[6] POTENTIAL BUGS AND OTHER NOTES
I should point out here that much of what SetCPU does is of a rather
dubious nature. Everything that's possible to do correctly under the 2.0
release of the OS, including CPU/FPU identifications and cache control, is
done via the approved 2.0 methods when running in 2.0, and via my own tricks
when run under 1.3 or earlier releases.
While it's impossible for an application to correctly use the MMU under
1.3 or 2.0, SetCPU attempts to be intelligent about its use of the MMU. It
will check for the use of the MMU by an agent other than SetCPU, and refuse to
modify the current MMU setup if such an alien MMU setup is found. For systems
with an unused MMU, SetCPU will do it's best to be safe about the modifications
it makes to the memory map. There may be problems with this program's MMU
code on the Amiga 3000, but based on the SuperKickStart and CPU programs that
are shipped with the first A3000s, this should not be of immediate concern,
since the A3000 comes with equivalent functionality. Should an A3000-safe
version of SetCPU eventually become needed, I'll make the attempt to track
down any A3000 bugs I can find. Just because you help design a machine doesn't
necessarily mean you have one to code and test on at home.
Finally, if you wish to contact me regarding bug reports, new
releases, contributions of cash or macadamia nuts, or pretty much anything
else, I can be reached at the below addresses.
-Dave Haynie
Logical Address:
PLINK: hazy
bix: hazy
usenet: {uunet,rutgers}!cbmvax!daveh
Physical Address:
284 Memorial Drive
Gibbstown, NJ
08027