[U-Boot] [PATCH] PowerPC MPC85xx: don't hang on read exception

[Andrew Klossner]

> Why not use the interrupt mode?
> If you use that mode, it will get more valuable information. Currently,
> U-boot have a little bit error detection mechanism if you configure
> the interrupts and enable the error interrupts.

I agree that this is the better approach, and I would be delighted if
somebody would write and submit that code for both u-boot and Linux.
It's a few hundred lines and takes careful testing, as we found with
our proprietary OS.

In the meantime, both u-boot and Linux are susceptible to processor
stalls.  This one-line patch replaces those stalls with exceptions.
The machine check exception handler won't diagnose the problem (e.g.,
it won't display "localbus parity error,") but at least we know that
something happened and we have a register dump with which to begin
analyzing the problem.

  -=- Andrew Klossner