[U-Boot-Users] Persistent Flash File System.

[Srivatsan]

Hi all,

    Thanks for the response. I will surely get back to you all and share
my experience once I get the appropriate numbers in hand (Regarding the
programming with JTAG). 

    There is another query (Hope this is not Off Topic]. I am required
to start a Persistent(Very important) File system at the booloader stage
and that flash file system must be present even after an OS boots up (In
our case it is Linux). 

1) Whether the above condition possible ?
2) What are all the design considerations I must keep in mind while
designing such File Systems?

Thanks everyone. 

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

-- 
See us @ Embedded/Electronica Munich, Nov 09 - 12, Hall A.6 Booth 513
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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