Re: [microblaze-uclinux] cache problems with uboot

[John Williams <jwilliams@xxxxxxxxxxxxxx>]

Hi Jean,

jean@xxxxxxxxx wrote:
> I'm working with a Spartan3E1600-Rev A board, and I'm doing the
> Petalinux from scratch method of build, in preperation for a board that
> we are building that's very similar to the 1600 board.
>
> I've built my system in EDK and created my bit file and have downloaded
> that to the FPGA over the usb interface with no problems.  I can power
> up the system and get to the FSboot prompt and upload the uboot image
> via ttyS0.
>
> When I go to download the images for u-boot-s and the image.ub over
> tftp, immediately after the image finishes downloading, the board
> freezes.  I did some testing and eventually figured out that if I do a
> "icache off" and "dcache off" before I download the images, then it's
> all ok.

hmm..  Are you able to connect to the MicroBlaze via XMD at this point, 
and determine the state of the CPU?  Can you cross-check the PC contents 
with the u-boot memory map / disassembly, to see where it is stuck?

> After I download the images and write them to flash, I can reboot the
> board and it boots up normally with no errors, right to the console
> login prompt.
>
> I was wondering if anyone knew what this might be a symptom of?  I've
> looked at the reference build that comes with petalinux and compared it
> to mine, and I don't see anything difference when it comes to the DDR
> and cache setup.  What should I be looking for that would cause this
> behaviour?  

I can't think of any reason why the act of loading the file via TFTP 
should cause a cache-related failure.

Of course, make sure the image is not overwriting any area of memory in 
use by u-boot, although if this was the problem then your cache 
disabling fixup should have no impact.

> Is my cache actually functioning properly once I get the
> board up and running?

The kernel will initialise and re-enable the caches at boot time, yes.

Regards,

John
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