Looking for help with System 7 kernel HACK.

Looking for help with System 7 kernel HACK.

Post by James Doy » Thu, 18 Jul 1991 02:59:53

        Help! I am working with a cluncky but sentimental old m68k unix
box and have lost some info on how to hack the kernel. Advice,suggestions
and incantations fro System 7 UNIX hackers would be immensely enjoyed if
you are willing to drop me a reply.

The Equipment:   68000 based system
                 Konan "taisho" smart hard/flopy disk controller board
                 UniSoft 68000 Unix System 7

The Problem:     I would like to add a larger disk drive to my box.
                 I did this long ago in the past but lost the notebook
                 that contained details on hacking the unix core image
                 with adb. I would like it if someone could refresh my
                 memory or point me in the right direction...

The Technique:   I basically remember the jist of how I did it long ago.
                 I opened up /unix with adb and poked around the symbol
                 table. Somehow, I got to a table of major/minor device
                 descriptors. For each minor device entry, there was a
                 POINTER to another data strcuture that contained device
                 specific information on the physical disk drive
associated with the major-minor device number. This physical device
descriptor contained information that was loaded into the Taisho Smart
controller board on startup. It contained stuff like # of heads,
write-precomp selection, cylinders, start/end sectors etc.

What I did was to explore this table and look at the device descriptor
for a know drive that was working with the system. Then, I figured out
where the information went, located an unused minor device node and
set its physical descriptor block to match my new drives parameters.
I modified the kernel with adb, rebooted, formatted the new drive and
then used mkfs.. It work fine with no problems.
Now, I'd like to do it again.. But, I forgot the detailes!

The Solution?  If anyone could provide me with System 7 standard SYMBOL
table names, data strcture formats and constants used in the generic
driver I would be greatly appreciative.

Thanks.   ....... Jim Doyle