Re: Linux Loaded on 486...what now

Linux/EMC folks,

Regarding setting up a 486 for Linux/RT Linux/EMC, others have written
that 486s are too slow to run the software properly. This is
particularly true when running the windowing environment (X Windows),
which is virtually required for the EMC. This, combined with the
differences in how 486s handle memory, make them much more difficult to
set up and use than Pentium machines. The main difference in setup as
far as the EMC is concerned is the fact that 486s can only set aside up
to, but not including, 1 MB of RAM. The EMC only uses about 500 KB so
this is not a problem.

Has anyone succeeded in using a 486 with the EMC?

I posted some details on how it should be done earlier. I stuck it at
the end of this message, in case anyone wants to try.

--Fred

------------previous post-----------
Regarding setting up Linux/RT Linux and shared memory on a 486 with 64
MB of RAM..., note that there is a pitfall with 486s and
shared memory: you can only allocate up to, BUT NOT INCLUDING, 1 MB of
shared memory. Fortunately the EMC data structure only occupies about
500K so this is not a problem. Set aside 768K so the numbers are easier,
which means bumping up the set-aside by 256K = 0x40000.

To set up LILO for this, you need make the /etc/lilo.conf append line be
this:

...
append="mem=0x3F40000"

Note that you can use the "0x" notation instead of the "m" or "M"
notation.

Next, change the emc.run (or whatever you call you run script) to pass
this to the motion controller via insmod, e.g.,

...
# install motion module in kernel
echo "installing motion module..."
insmod -f plat/rtlinux_09J/lib/steppermod.o SHMEM_BASE_ADDRESS=0x3F40000
PARPORT_IO_ADDRESS=0x378
...

And finally, make the corresponding change in the INI file, e.g.,

...
[EMCMOT]
...
SHMEM_BASE_ADDRESS = 0x3F40000
...

This 3-part harmony sets aside the shared memory at boot time, tells the
motion controller what it is, and tells the task level controller what
it is. Note that the motion controller can't read INI files so we have
to live with passing it as a symbol=value argument to insmod.