64-bit PCI transfers
64-bit PCI transfers
- Subject: 64-bit PCI transfers
- From: Michael George <email@hidden>
- Date: Wed, 11 Dec 2002 16:38:29 -0500
According to specs, the PCI bus in the G4s can do 64-bit transfers, at
least for DMA transfers.
GCC and the include files on OS X have the "long long" data type, which
is 64-bits. However, one of our hardware designers said that when he
tested 64-bit IO from the processor to the device on the PCI bus, that
the high-order bits were all cleared and data was only in the bottom
long.
I am wondering if it is indeed the case that CPU <--> PCI bus transfers
are limited to 4 bytes, or if we're overlooking something.
Is anyone doing 64-bit CPU <--> PCI transfers?
Thanks!
-Michael
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