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Addressing on SAMA5D2 Xplained

Posted: Wed Apr 25, 2018 6:53 pm
by 3F800000
I'm entirely new to the SAMA5D2 and the eval board.

With the XULT running the provided Linux kernel (blue LED blinking) I used the IDE (IAR EW) to break into debug. The code appears to be running in the address range of 0xC01XXXXX. (Based on the Program Counter and disassembly listings.)

The kernel is identified as: Linux version 4.9.87-linux4sam_5.8 (gcc version 7.3.0 (GCC)

Can someone explain the address space? The data sheet suggests 0xC0000000 is mapped to the "NFC command Register". I was expecting the code to be running in RAM, since U-Boot loads the kernel from flash to 0x22000000. (Even though the datasheet lists that address as in the region of "DDR Chip Select", which also isn't clear.)

Perhaps the answer is the part is using it's MMU and a virtual memory scheme?

Thanks for any insight you can provide.

Re: Addressing on SAMA5D2 Xplained

Posted: Wed Apr 25, 2018 11:29 pm
by blue_z
3F800000 wrote:The code appears to be running in the address range of 0xC01XXXXX.
...
Perhaps the answer is the part is using it's MMU and a virtual memory scheme?
Yes, the addresses you are looking at refer to virtual memory.
When using an "address" you need to be cognizant of which address space it belongs to.
E.G. during the Linux boot, you could be dealing with addresses for NAND flash, physical memory, and virtual memory .

Regards

Re: Addressing on SAMA5D2 Xplained

Posted: Fri Aug 03, 2018 5:57 am
by Trilok
Hi @blue_z,

I'm new to this processor. I want to start without OS using some IDE like IAR Embeddded studio, Keil DS-MDK. But I'm unable to get started. I researched many online tutorials, no one is is giving the clear picture about any of IDEs. Many of community people saying that IAR embedded workbench will support SAMA5D2. But, this tool is not giving the clear picture about How to get started with SAMA5D2.

Hoping for response, I appreciate your valuable feedback/response.

Thanks/Regards

Trilok

Re: Addressing on SAMA5D2 Xplained

Posted: Fri Aug 03, 2018 2:13 pm
by tsvoipio
For starters, you need the datasheet of the chip from:
<http://ww1.microchip.com/downloads/en/D ... 01476B.pdf>

It is somewhat heavy reading (little over 2600 pages).

For the virtual addressing in Linux, get e.g. the book 'Understanding the Linux Kernel'.

--

-TV

Re: Addressing on SAMA5D2 Xplained

Posted: Fri Aug 03, 2018 11:15 pm
by blue_z
Trilok,

I have not used any IDE, and therefore cannot offer any specific advice.

Trilok wrote:Many of community people saying that IAR embedded workbench will support SAMA5D2. But, this tool is not giving the clear picture about How to get started with SAMA5D2.
The IAR website clearly claims to support the SAMA5D2.
If you're also using the Microchip Software Package, then be sure to study the README.md file and inspect the scripts/ directory.

Regards