MmMapIoSpace is it really uncached??

bigus_dingus_at_yahoo.com
Date: 01/24/05 

Date: 24 Jan 2005 14:12:07 -0800

I am using the MmMapIoSpace() system call to attempt to access a
physical address. I am passing in False for the parameter "CacheType"
as I most definitely do _not_ want this access to go through the
processor's cache. However, looking at the bus cycle, I don't believe
that I am getting an un-cached access. Within OEMAddressTable, this
area is mapped to virtual address 0x80000000 which I understand is
un-cached.
So, my question is this,

Is it possible to get an un-cached address from MmMapIoSpace() if the
corresponding entry within OEMAddressTable is cached?

...background:
Using a Sharp arm processor, the bus will not toggle the chip select
when sequential accesses to the same chip select areas occur. Some
hardware has a problem with this. I am creating a barrier function to
read a different chip select area between successive reads. In the
barrier function, if I read a cached area, then a bus access does not
occur. This is what I am seeing when using MmMapIoSpace(my_address, 4,
FALSE).

anyone...anyone...
Eric

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