Help: Tweaking /unix file system code with adb

[dmanning at ecs.umass.edu]

Here's the scoop... I picked up an old klunker at a surplus sale. It is a 
68010-box with a V7 port of Unix on it. It uses a bunch of different 
Multibus cards for hardware.

Originally, the Unix was meant to boot off a 20 MB 8-head RODIME drive. The
machine uses an intelligent controller. When I wanted to put my 40 MB Atasi
drive onto it, A neighbor and Unix wizard came over and did something magical
to get the 40 MB drive to work w/out writing a device driver!

He went into adb and opened the image of the unix core (i.e. /unix). He
then used the major/minor device numbers for the previous drive (the 20 MB
rodime) to access some data structures in the unix core image. From that,
he mentioned that each major/minor device has associated a structure that
contains #cylinders, #heads, sectors/track, seek time etc. He simply went
replaced the existing parameters for the 20 MB drive with the 40 MB drive
using ADB. Then, of course, we rebooted the system from another volume and
did mkfs to create a new 40 MB volume. It has worked fine since, but now I
want to put an even larger drive on the system! Can anyone of the Unix
wizards point me in the direction needed so I can locate this data structure
using adb and make the appropriate changes myself? Sorry, I do not have 
source code! Apparently some of the symbol names are consistent from port to
port of V7.


P.S. I know, I should have thrown this beast out years ago but I am a poor
     undergrad and I need to keep the machine going so that I can continue
     work on my Minix and GNU projects.


Thanx........ j. doyle c/o d. manning
Please send correspondence to s2465499 at tethys.ucc.umass.edu