asymmetrical target and master interfaces

[v_chau@emulex.com (Vi Chau)]

Hi, Everyone,

I have a question regarding the setup and operation of PCI devices that have
asymmetrical target and master interfaces.

We are currently developing an ASIC for a PCI interface. The PCI logic includes
a target interface that supports dual-address cycles (>32-bit address) and a
master interface that only supports 32-bit address.

What I heard from our driver writers is that this present a problem for them
because systems and OS's tend to be confused when they see our BAR's supporting
64-bit addresses and assume that all addresses used by this device would be
64-bit. This causes a lot of headache for the drivers.

Does anyone has any experience with such a device? Do you have the same sort
of problems?

Given that operating systems such as Windows NT are only 32-bit, how does it
react to a PCI device that tells the OS that it can be mapped anywhere within
the 64-bit address range?

Thanks in advance for your ideas and answers.



Vi chau
Emulex Corp.
3535 Harbor Blvd.
Costa Mesa, CA 92626
(714) 513-8132
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