RE: [microblaze-uclinux] Kernel boot problem ( Michael Simek Wiki )

Dear Jhon

Thanks for your guidance, I understood that XMD can not understand virtual addresses, however i could not find out how I should solve the problem. you have wirtten that i should do a subtraction to reach to physical address from virtual one.

however my problem is that, XMD dow command simply can not load the kernel. It generates errors, it can not understand what ix 0xc0000000 address. how should i solve this one? i mean how should i tell XMD that 0xc0000000 is a virtual address?

my problem for now is not the relationship between these two addresses, but it is how to load the kernel into memory using XMD at all?

Thanks

Date: Tue, 27 Oct 2009 22:02:29 +1000
Subject: Re: [microblaze-uclinux] Kernel boot problem ( Michael Simek Wiki )
From: john.williams@xxxxxxxxxxxxx
To: microblaze-uclinux@xxxxxxxxxxxxxx

Hi Mohammad,

On Tue, Oct 27, 2009 at 9:38 PM, Mohammad Sadegh Sadri <mamsadegh@xxxxxxxxxxx> wrote:

Dear Michal ( and others )

You were correct,
I added the following change into kernel configuration:
- Platform Options ---> Physical Address where Linux kernel is : 0x44800000

Again we have problem with XMD, when running dow command, it persist on there is no 0xc0000000 address

XMD does not understand virtual addresses, only physical. You must convert virtual addresses to physical when using XMD. A simple example

PHYS_base 0x50000000
VIRT_base 0xc0000000

To convert a virtual address to physical, for inspecting with XMD, you must subtract (0xc0000000-0x50000000 = 0x70000000) from each virtual address.

It's too late for me to do anything other than trivial hex arithmetic in my head so I didn't choose your physical address, but you get the idea!

I added the following changes into kernel configuration to solve the problem:

- In "Advanced Setup" I enabled "Prompt for advance kernel configuration options"
- In "Advanced setup" I enable "Set custom kernel base address"
- I set the custom kernel address to 0x44800000

You cannot do this - this is the virtual address of the kernel, it must not be the same as the physical address. You should not change this from the default - 0xc0000000.

Now, in XMD , dow can run successfully, and I can run the kernel,
here is the outcome:

early_printk_console is enabled at 0x84000000
Ramdisk addr 0x00000003, Compiled-in FDT at 0x44a2d49c

and kernel stops working completely!

Overlaid / overlapping physical and virtual address spaces is almost certainly the cause.

Regards,

John

--
John Williams, PhD, B.Eng, B.IT
PetaLogix - Linux Solutions for a Reconfigurable World
w: www.petalogix.com p: +61-7-30090663 f: +61-7-30090663

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