> it is the sparc port's fault.
   > 
   > due to several issues, the sparc port is by default limited to what
   > you see above.  you can work around this by editing the sparc
   > machdep.c to change the code that limits these values, and also
   > decreasing MAXBSIZE so that kernel memory is not overused.  i
   > personally use these values:
   > 
   > 	options         MAXBSIZE=16384
   > 	options         NBUF=2048
   > 	options         BUFPAGES=4096
   
   Ah, would this be one of the issues:

huh.
   
   esp0: DMA error; resetting
   esp0: waiting for SCSI Bus Reset to happen
   sd1: disk label read error
   sd1(esp0:3:0): max sync rate 4.80Mb/s
   cannot mount root, error = 6
   root device (default sd1a):
   
   I get that (and a bunch of DMA errors before that) as soon as I tweak
   MAXBSIZE, NBUF and BUFPAGES. Will I just have to live with 512kb buffer

huh.

i have 6 sun4c-class machines.  5 of them are running kernels with
the above, but the 6th will not work.  esp craps outs similarly to
the above when attempting to mountroot.  i haven't tried lowering
these values to see if those are causing the problem, but i will..

   cache (and wait hard for UBC which will hopefully fix it...)?

ubc should fix all these problems and more ...