Raspberry/ARM processor halts when invalidating tlb

[Alan Cudmore]

Hi Hesham,
I don't have an answer for you, but you may be able to find some help or 
example code on the raspberrypi.org forums.
A couple of examples:
http://www.raspberrypi.org/phpBB3/viewtopic.php?t=40183&p=336705
http://www.raspberrypi.org/phpBB3/viewtopic.php?t=40665&p=332205

I avoided the MMU setup on the raspberry pi BSP, because I knew that the 
GPU based bootloader set up the memory for the ARM CPU. More info on the 
whole boot process here:
http://elinux.org/RPi_Software

Another nice thing to have for work like this is a JTAG debugger setup. 
I hope I can get an inexpensive setup for mine before I try to add any 
more drivers.
The readme at the repository below has some good info on setting up JTAG 
on the raspberry pi:
https://github.com/dwelch67/raspberrypi/tree/master/armjtag

Alan


On 8/22/2013 6:48 PM, Hesham Moustafa wrote:
> Hey all,
>
> I am working on Raspberry Pi BSP which has ARM1176JZF-S (ARMv6) 
> processor on it. Here is what I am doing that causes the processor to 
> halt:
>
> At BSP startup, specifically in bsp_start_hook_0 function, I call 
> another function that :
> 1- Initialize first level page tables (sections) with READ/WRITE 
> permissions.
> 2- Invalidate TLB.
> 3- Enable MMU, Cache, Protection bits in control register.
>
> Initialization is done correctly and the program reaches my 
> application (test case), which tries to update first level page table 
> entries to force another protection attributes for a memory region. At 
> this part, after, or before, modifying the page table entry, I try to 
> invalidate TLB but the program halts there. I disable MMU and Caches 
> during updating page tables and invalidating TLB.
>
> When removing the function call that invalidates the TLB, the program 
> proceed to the end successfully.
>
> Not sure why the processor halts when trying to invalidate the TLB "at 
> the second time". I hope someone can tell me the reason.
>
> Regards,
> Hesham
>
>
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