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" <[EMAIL PROTECTED]> To: <linuxppc-embedded at lists.linuxppc.org> 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: > > > > 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 > > 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 > > 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 > > > > ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
