Fix for 4.3BSD-Quasijarus bootstrap on CMD SCSI controllers

Josh Dersch derschjo at
Tue Jan 3 00:58:54 CST 2017

Hi all --

Thought I'd share this fix with you all just in case someone in the 
future might make use of it.

Long story short:  Got myself a CMD 710/M UNIBUS SCSI controller with 
the intent to use it in my VAX-11/750, running 4.3BSD-Quasijarus.  
Unfortunately it won't boot (it hangs shortly after "loading boot" is 
printed to the console).  VMS boots, NetBSD > 1.6 or so boots, Ultrix 
boots, but no luck with 4.3BSD.

I spent some time adding some debug spew to the bootstrap (on SIMH) and 
testing (on the 750), and the hang is inside udcmd() in 
sys/vaxstand/uda.c.  I then stumbled on this usenet post:!msg/alt.sys.pdp11/61LZNTo9Dgg/Q6dI9om_LIEJ

Which indicates a similar problem with a Viking controller on a 
different 4.3BSD variant.  The code in Quasijarus is a bit different, 
but the cause is the same.

The fix is:

Change line 155 of sys/vaxstand/uda.c from:

     if(u->uda_ca.ca_rspint ==0)


     if(u->uda_ca.ca_rspdc & MSCP_OWN)

Rebuild, and re-run disklabel to replace the bootstrap.

Hope that helps someone else someday...

- Josh

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