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On Feb 3, 2004, at 4:13 PM, Frederick Bruckman wrote:

> Originally, I tried to use bus_space_barrier(...,
> BUS_SPACE_BARRIER_READ_BEFORE_WRITE) before pci_conf_write() [*].
> My thinking was, that the compiler would see the registers as being
> set by pci_conf_read(), whereas you might rather think of them as
> being set by bus_space_barrier(), as a side-effect; ergo "volatile".

PCI configuration space does not require barriers, and you don't need 
volatile there, either.  (PCI configuration space is handled through a 
functional interface, and so there is already an implicit memory 
clobber.)

         -- Jason R. Thorpe <thorpej@wasabisystems.com>


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