Subject: Re: 64-bit memory fun with an adaptec 3950U2B..
To: None <>
From: Jason R Thorpe <>
List: tech-kern
Date: 03/14/2000 08:29:30
On Tue, Mar 14, 2000 at 11:18:16AM +0100, Frank van der Linden wrote:

 > It could make sense to bump bus_addr_t to 64 bits on LP64 platforms to
 > support 64bit PCI buses, however, an awful lot of code out there deals
 > with devices that can at most address 32 bits across the bus, i.e. that
 > bus_addr_t <= 32 bits, and that it can be programmed into 32bit wide
 > card registers. It will need some work to make the code accept that
 > bus_addr_t is 64 bits, although it's doable.

On LP64 systems (like the Alpha), the bus_addr_t and bus_size_t types
are already 64 bits.

 > I've also been told that on Alphas, when a 32bit adaptec card is put
 > into a 64bit slot, pci_mem_find will find 64bit memory. So I think
 > that pci_mem_find should find either type, and only fail if the
 > upper word is != 0.

Gross!  What happens if the BARs aren't laid out properly to decode the
extra word?

        -- Jason R. Thorpe <>