Re: How to visit physical memory above 4G?

[Julian Elischer]

On Thu, 2 Aug 2001, Mike Smith wrote:

> Julian is on crack.  DAC (Double Address Cycle) is a relatively recent 
> addition to PCI that allows 32-bit cards with 64-bit savvy logic to talk 
> to host memory using 64-bit target addresses.



well "day 1" was an exageration, but my 1995 PCI stuff already includes
it.

Crack? no..  optimism, maybe..
 
> Older systems used a scatter-gather mechanism to present a virtualised 
> view of the system's physical address space to the PCI bus (typically 
> you'll see this in Alpha systems).


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