[U-Boot-Users] u-boot for Vertex4-based board.

Markus Klotzbücher mk at denx.de
Wed Feb 14 17:21:08 CET 2007

Dear Leonid,

"Leonid" <Leonid at a-k-a.net> writes:

> On Tuesday, February 13, 2007 10:55 PM Markus Klotzbücher:
>> > I'm porting u-boot on Vertex-4 based board (with PPC405 inside);
> I'm
>> > trying use ml403 u-boot as example. I have first stage boot
> loader,
>> > taking my u-boot image from serial and loading it to SDRAM, u-boot
> is
>> > configured to boot from main memory. 
>> Are you aware that this setup is strongly discouraged? Have you read
>> this:
> dInRAM?
> [Leonid] The answer in DULG FAQ chapter you are referring to doesn't
> say that such practice is bad, it simply states that u-boot doesn't
> support such an option. That could be truth in the time of DULG FAQ
> writing but now there are many platforms, naturally using 3-stage
> booting. For example, ATMEL ARM boards have small boot program which
> fetches u-boot from flash, loads it to RAM and then starts. I would
> like to hear why do you think it's so bad, but in any case this way
> u-boot is normally used for such boards (at91rm9200-ek for instance).

I didn't say it's bad to do this, I just wanted to point out that
starting U-Boot from RAM is not the standard way and you might
experience difficulties. Having said that, yes, I'm well aware there are
boards doing this, to be honest I have done it myself. Sometimes there
is no other way.

> In my case I probably could change EDK project to put flash on the end
> of the memory, but I prefer to load u-boot via XMD debugger or serial
> directly to RAM - much more convenient for debugging - since otherwise
> I will need to burn flash each time I change something and I cannot
> use BDI2000 on this board. Xilinx tools are not that convenient for
> frequent flash burning.

Well, I guess I would still burn U-Boot to flash if I had the
choice. This setup has been tested much better. But as you seem to know
what you are doing, it's ok.

Best Regards


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