Hobbled NVAX - test-drb@ccmp.vtda.org

18 Jan 2003

Antonio Carlini &lt;arcarlini(a)iee.org&gt; wrote:

...
  I doubt that non-hobbled firmware exists. I doubt you
 could just use the UV3100-96 firmware upgrade on a 
 UV3100-85 and have it work. In fact, I guess the firmware 
 is the same but it looks at the machine's hardware (e.g.
 size and config of backup cache or something like that)
 to determine what it is running on, and disables the VIC
 if it thinks the machine is a UV3100-85. 
Umm, I don't think so. It looks like the firmware is the only difference
between M85 and the equivalent M9x model and the hardware is the same. In this
case flashing M9x firmware would obviously give you the M9x model. But even if
the M85 board was really different in B-cache or something from all M9x models,
I doubt that the firmware could detect this by "looking at the hardware". AFAIK
it's the firmware that has to tell the chips how the board is configured, not
the other way around.

If indeed the hobbled and non-hobbled firmware are the same code, what it looks
at to make the decision is most probably a flag in the second longword of the
ROM.

...
  The easiest thing to do would be to try reenabling the
VIC.
 If that is not enough, you would have to find the bit of code
 that disables the VIC and NOP it out. 
Well, if it munges the microcode I would go for option 2 in any case.

BTW, do you know for sure that it really munges the microcode and not just
disables the VIC in the same way normal caches from CVAX onward can be enabled
and disabled as you like?

MS