Re: NetBSD and VMEbus RAM

[Chris Hanson <cmhanson%eschatologist.net@localhost>]

On Aug 13, 2020, at 1:32 PM, Michael Thompson <michael.99.thompson%gmail.com@localhost> wrote:
> 
> 
> The MM-6230 manual says "The user must initialize the memory module to allow the parity generator to store ODD parity otherwise the module will assert BERR* for any subsequent read cycle."
> 
> The first time that NetBSD reads an uninitialized location from this RAM it will cause a bus error. BetBSD might scan RAM locations to see how much RAM is available.
> 
> You can either write an initialization routine that writes to all memory locations on the board before NetBSD touches it, or you can move jumper E1-E2 to E2-E3 to prevent the board from causing a BERR*.

Indeed, I read this as well, so before installing the board yesterday I set the jumpers to not generate BERR* on parity error and to auto-recover. The board comes up with the parity error LED on, and then my program that zeroes the board causes it to turn off. I did this, shut down NetBSD, specified the board addresses in 0xFFFC000[0-4], and upon reboot that’s when I saw the failure I reported.

  — Chris