Re: [microblaze-uclinux] Running uClinux with 8M memory?

[John Williams <jwilliams@xxxxxxxxxxxxxx>]

Hi Welson,

Welson Sun wrote:

> I have went through the EDK tool flow and written a simple uart test program
> for it. It can run out of bram or I can init the BRAM with the xmd_stub and
> I can use XMD to download and debug the software. Also, I can make the code
> run out of ZBT SRAM.

Sounds like a good starting point.

> I would like to try uClinux quickly on this platform, so I wonder if the
> demo image will just work if I modified my SRAM memory to the original DDR
> space,at least the starting address? Cuz looks like the current SRAM on
> Memec board is not used by uClinux. Is 8M enough? Or in my case, I have to
> modify the kernel source and recompile it to make it work on my platform?
> 
> Sounds like naive questions, but any feedback is appreciated.

Not naive at all - what you are proposing is the best way to go. 
Basically, I recommend that you make your platform look as much as 
possible like the standard mbvanilla platform, and start from there.

I think your idea is a good one.  Aurash's other comment about stubbing 
the serial port isn't a bad idea either, although in this instance it 
would be prety easy to remove the 2nd port from the driver.  In 
linux-2.4.x/arch/microblaze/kernel/xmbserial.c, there's a struct 
initialiser on or around line 60 that specifies the serial ports - it 
should be obvious how to modify it to support just one serial port.

Also, to accomodate the changed memory size, edit the file 
linux-2.4.x/include/asm-microblaze/mbvanilla.h, around line 55.

The other hardware/platform related items that can bite will be the use 
of hard multipler/divider core in the microblaze, hard vs soft barrel 
shift, and also the caches as Aurash mentions.

These need to be consistent with mbvanilla or else you will get all 
sorts of curious and cryptic errors.  However, it's a simple matter to 
adjust the kernel configuration on these items.

Regards,

John





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-- 
Dr John Williams, Research Fellow,
Embedded Systems Group / Reconfigurable Computing
School of ITEE, The University of Queensland, Brisbane, Australia
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