Re: IBM 440GP 36-bit addressing

Hi All,

Thanks for your information. I have few more doubts.

By going through the code, I understood that ioremap64() is used for mapping
the 36-bit real address onto 32-bit effective address space. How this
mapping information is conveyed to user applications ?

If I am writing assembly instructions to access 440GP registers, do I have
to pass 36-bit real address or 32-bit effective address ?

Physical address map of 440GP provides information only about Real
addresses.  How can I convert these real addresses onto effective addresses
? Do I have to write a TLB entry regarding my addresses ?

Thanks and Regards,
Vishwa


----- Original Message -----
From: "Hollis Blanchard" <redacted>
To: <redacted>
Sent: Friday, August 23, 2002 8:30 PM
Subject: Re: IBM 440GP 36-bit addressing

On Fri, 2002-08-23 at 10:00, Vishwanath wrote:

quoted

I am new to PPC Linux. I am working on IBM 440 GP board. I am using
MontaVista Linux source code. I didn't understand how 36-bit addressing

is

quoted

taken care in this code. If an application has to access the a memory
location in SDRAM of 440 GP or its internal peripheral registers,

whether it

quoted

has to pass 36-bit address or normal 32-bit address.

It's a 36-bit real address space, but 32-bit effective (aka "virtual").
Applications, which run entirely in effective address space, have no
reason to think about such things and require no modification.

The kernel has to care about the real address space, mostly when you
want to ioremap (all the on-chip peripheral addresses are higher than
4GB as I recall) a 36-bit real address to a 32-bit effective address so
you can use it in the kernel (which also runs in effective mode).

-Hollis

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