[Coco] NitrOS-9, Cobbler and Fragmented Boot Files

[Robert Gault]

Darren A wrote:
> Wasn't NitrOS-9 modified to work with a fragmented boot file?
>
> I'm currently working on a new driver for the CoCo SDC. After building a
> new DSK image I usually opt to change the screen width to 40 columns by
> entering:
>
> xmode /term col=28 sty=1
> cobbler /dd
>
> On recent builds (as the driver code has grown in size) Cobbler now fails,
> reporting that the boot file is fragmented. This renders the disk
> un-bootable and I have to move a fresh copy of the DSK image onto the SD
> card. I can avoid the problem by using dmode to set sas=80 before running
> cobbler, but can't reduce sas later without getting a fragmented file again.
>
> If NitrOS-9 has solved the fragmented boot limitation, shouldn't Cobbler be
> changed so that it doesn't abort in that situation? Is there something else
> I should be using instead of Cobbler?
>
> Darren
>

We would need to patch cobbler but I think you can get your fragmented disk to 
boot if the following is true. Cobbler actually saves the kernel and OS9Boot 
before checking for fragmentation.

By looking at the code in boot_common, you can see that it checks LSN0 to see if 
the boot size (DD.BSZ) is zero. When true, a fragmented boot is assumed and the 
file descriptor is used to find the fragments of OS9Boot.
So, use dir -e to obtain the location of the OS9Boot file descriptor and then 
use dEd to put that value in DD.BT ($15-$17) and put $0000 in DD.BSZ ($18-$19).

If the above works (let us know), then cobbler can be changed to omit the 
fragmentation warning and set DD.BT and DD.BSZ as described above.

Robert