The FreeBSD Diary

For the technical minded, here's something which might mean something to you:

$ dmesg
Copyright (c) 1992-1998 FreeBSD Inc.
Copyright (c) 1982, 1986, 1989, 1991, 1993
   The Regents of the University of California.  All rights reserved.

FreeBSD 2.2.8-RELEASE #0: Mon Nov 30 06:34:08 GMT 1998
    jkh@time.cdrom.com:/usr/src/sys/compile/GENERIC
CPU: i486DX (486-class CPU)
real memory  = 33554432 (32768K bytes)
avail memory = 30334976 (29624K bytes)
Probing for devices on PCI bus 0:
chip0 <intel 82424ZX (Saturn) cache DRAM controller> rev 2 on pci0:0:0
ncr0 <ncr 53c810 fast10 scsi> rev 1 int a irq 11 on pci0:1:0
ncr0 waiting for scsi devices to settle
(ncr0:0:0): "DEC RZ25M    (C) DEC 0680" type 0 fixed SCSI 2
sd0(ncr0:0:0): Direct-Access 
sd0(ncr0:0:0): 10.0 MB/s (100 ns, offset 8)
510MB (1046206 512 byte sectors)
(ncr0:1:0): "SEAGATE ST5660N 0592" type 0 fixed SCSI 2
sd1(ncr0:1:0): Direct-Access 
sd1(ncr0:1:0): 10.0 MB/s (100 ns, offset 8)
520MB (1065664 512 byte sectors)
(ncr0:6:0): "NEC CD-ROM DRIVE:841 1.0" type 5 removable SCSI 2

You can clearly see that the ncr SCSI device is found and works fine.  However, we had no such luck with 3.*.

Index: pcibus.c
===================================================================
RCS file: /usr/cvs/src/sys/i386/isa/pcibus.c,v
retrieving revision 1.41
diff -C2 -r1.41 pcibus.c
*** pcibus.c    1997/12/20 09:04:25     1.41
--- pcibus.c    1999/06/07 11:58:58
***************
*** 260,265 ****
        }

!       cfgmech = 0;
!       devmax = 0;
        return (cfgmech);
  }
--- 260,265 ----
        }

!       cfgmech = 2;
!       devmax = 16;
        return (cfgmech);
  }

# cd /usr/src/sys/i386/conf
# cp GENERIC NCR
# config NCR
# cd ../../compile/NCR
# make depend
# make

But wait?  How did I create that kernel in the first place?  I didn't have 3.2-Release installed, so how could I create a 3.2-Release kernel?  This is a classic chicken-and-egg situation.  The answer is easy: I asked someone who has 3.2-Release to create the kernel for me.

So.  Now I have a patched 3.2-Release kernel.  But what use was it?

# mount /dev/fd0 /mnt
# cd /mnt
# ls
boot              boot.config     kernel.config   kernel.gz

That kernel.gz file is just a plan old kernel which has been gzip'd.  There's nothing special about.  It's just a GENERIC kernel which anyone can create.  For that matter, you could replace that file with your own kernel and it would still work as a boot floppy.  So I just replaced that kernel with my own.  You might also be interested in compiling a kernel on another machine.

If you are doing the above, you may wish to add the following option into your kernel:

options         INTRO_USERCONFIG      #imply -c and show intro screen

This option forces the visual configuration screen.  This can be useful but it not recommended for the final kernel.

# cd /usr/src/sys/compile/NCR
# gzip kernel >> kernel.gz
# mount /dev/fd0 /mnt
# cp kernel.gz /mnt
# umount /mnt

The important difference is that before I rebooted, I used the "emergency holographic shell" that's created on vty4 to replace the default 3.2-Release kernel with my own custom 3.2-release kernel.  Here's how I did that.

REMEMBER to take out the second floppy and put in the first floppy before doing this.   The first floppy contains kernel.gz.  If you don't, all you'll find is mfsroot.gz, which is of no use to you for this exercise.

# cd /
# chflags noschg kernel
# cp kernel kernel.orginal.3.2-RELEASE
# mount /dev/fd0 /mnt
# cp /mnt/kernel.gz .
# umount /mnt
# gunzip kernel.gz
# chflags schg kernel

Then I went back to the install and did an exit.  The system then shutdown and rebooted.  And I had 3.2-Release installed!

WOO HOO!