Re: PXA-255 RAM offset Problem

Hi All,
    apparently i did not understand the booting sequence of Linux too 
well. Previously my kernel was hanging because i had enabled 
CONFIG_DEBUG_LL, which apparently was trying to access the PXA255's uart 
using the physical address location given in debug-armv.S, even after the 
page table's were initialized and mmu enabled. After i remved that 
CONFIG_DEBUG_LL and replaced 0xa0008000 with 0xc0008000, linux booted 
perfectly.

Mayank

 On Tue, 30 Sep 2003, Mayank Sharma wrote:

> Hello Listers,
>      I have a very basic question with respect to the physical offset 
> where DRAM is placed. I am working on bringing Linux up on a PXA-255 based 
> custom board that we built here at Impulsesoft.
>      I downloaded the 2.4.19 kernel, applied rmk's patch 
> (www.arm-liunx.org) and pxa's patch (www.handhelds.org) and modified it to 
> suit our hardware. I got the current bootloder up and running on the board 
> and then i tried booting linux. While booting linux it went through the 
> head-armv.S code and ^i thought^ it hanged before calling the start_kernel 
> function from the assembly. I figured it might be because the TEXTADDR 
> variable in arch/arm/Makefile was set to 0xc0008000, but i had loaded the 
> kernel at 0xa0008000 (PXA's RAM offset is 0xA0000000), So i changed the 
> TEXTADDR to 0xa0008000, now the start_kernel function was called, but when 
> it was trying to access bootparams(physical 0xa0001000, Virtual 
> 0xc0001000) it again hanged. Out of ideas i just changed the PAGE_OFFSET 
> in include/asm/arch/memory.h to 0xa0000000. And then it started booting 
> up. 
>     I am not sure if the changes that i have done are right because i 
> assume that a lot of people have got their linux up and running on PXA-255 
> without changing the Makefile or the memory.h. So i want to know where 
> exactly am i going wrong? and what is the better way to circumvent this 
> problem.
>     Probably i think the MMU is not initialized properly so the physical 
> address 0xA000000 is not getting mapped to 0xC0000000.
> 
> 

-- 

-Mayank
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Without facts, the decision cannot be made logically.  You must rely on
your human intuition.
                -- Spock, "Assignment: Earth", stardate unknown