Re: Incrementing volatiles?

[Andreas Schwab <schwab at issan dot informatik dot uni-dortmund dot de>]

"Philippe De Muyter" <phdm@macqel.be> writes:

|> Sorry to be slightly off-topic, but this discussion reminds me a problem
|> I encountered some months ago when writing a driver for a VME board in
|> an AIX powerpc environment.  Although I had declared all the registers
|> of the chips on the board as volatile, and compiled my driver with gcc,
|> I saw with a logic analyser on the VME bus that the accesses to the
|> register on the board were not done in the order I had written them.
|> To solve that problem, I had to manually add asm("eieio") after each
|> access to a volatile register.  Should gcc not do that for me ?

I don't think so.  It's the responsibility of the system software to
make sure that accesses to hardware registers are uncached and serialized.

-- 
Andreas Schwab                                      "And now for something
schwab@issan.informatik.uni-dortmund.de              completely different"
schwab@gnu.org