[U-Boot-Users] Univesal bootloader in 2 stages

[Srivatsan]

Thanks for the answer Mr.Wolfgang Denk.

Since my hardware is customized, to run the hardware for the very first
time with a bootloader, programming 200K will take a lot more time with
a JTAG interface [Thinking from manufacturing angle]. That’s the reason
I wanted to have the bootloader to be split into 2.[So that programming
only around 10K will not take a lot of time compared to the whole
bootloader].

Do you have any suggestion for this type of a scenario?

Thanks for the answer.

Regards,
C.R.Srivatsan

-----Original Message-----
From: wd at denx.de [mailto:wd at denx.de] 
Sent: Friday, November 05, 2004 4:13 PM
To: Srivatsan
Cc: u-boot-users at lists.sourceforge.net
Subject: Re: [U-Boot-Users] Univesal bootloader in 2 stages 

In message <000401c4c30a$578db310$4501a8c0 at bgcw301> you wrote:
> 
>      I understand that uboot works in 2 stages, one before RAM is
> initialized and the other after RAM is initialized.

You understand that these are just two different states of  operation
within the same code?

>      But my requirement is, I would like to load the First stage of
> uboot into Flash, then get the second stage of the boot loader thro' a
> fast Ethernet(This means that I require a Ethernet driver to run from

This is no possible with U-Boot. There are no  separate  images,  but
just  one  program which is running first in flash, and then - agfter
relocation - continues to run from RAM.

> Flash). In addition I would also like to start a Flash File system in
> first stage itself. Here's a summary
> 
> Uboot -- I stage [Running from Flash]
> CPU setup. 
> Ethernet driver, support for TFTP.
> Flash driver.
> Flash file system.
> Uboot - IIstage [Running from RAM]

That does not work. First, you cannot have an ethenret driver  before
initializing  the  ram (where would you buffer the network packets?).
Second, with most flash types  you  cannot  access  the  flash  (like
erase,  program,  or  even  read  status  information)  while you are
executing code from the same device. You MUST be  running  such  code
from some other memory.

> Would like to know whether the above split up of Uboot is feasible?

No, this is not possible.

What makes you think you need such a  configuration?  Why  can't  you
just use U-Boot as is?

Best regards,

Wolfgang Denk

-- 
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Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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