[U-Boot-Users] Cascaded U-Boot setup question

Mike Wellington wellington at lucent.com
Tue Apr 13 17:05:40 CEST 2004

   I have multiple Xilinx ML300 boards.  Each one has its own
ip address.  Each board may have different boot parameters - baud
rate, root file system, etc.  Basically each board needs its
own boot parameters stored in some kind of non-volatile storage.
But there is no working non-volatile storage on these boards (yet),
until I get I2C EEPROM working.  Each board just boots from its
copy of u-boot (which is generic) from the microdrive.  Now, I
could sit at each board and as it comes up, stop the autoboot
and manually enter the parameters, but that's clunky.  What
I want to do is build a board-specific u-boot with parameters
that are specific to that machine-name.   So my boot
process would be:

1)  Load the generic u-boot off the microdrive.  It knows what
  *machine-name*  is and where to get the next stage at.

2)  Use the generic u-boot to download a machine-specific u-boot,
     uboot-<machine-name>, which I can recompile and change at will
     since it resides on my tftp server.  I don't have to rewrite
     the microdrive every time I want to change the boot parameters,
     all I have to do is build a new *second-stage* machine-specific
     u-boot-<machine-name> and put it in the /tftp download directory.

3)  Run the 2nd u-boot (u-boot-<machine-name>)
   (which has the machine specific parameters)
     and let it boot the kernel with the arguments that I want.

I tried downloading an uncompressed u-boot and loading it at 0x20000,
then just saying "go 0x20000" and it doesn't work, it generates and
illegal instruction exception.  (is the starting address of u-boot not
at the beginning of the .TEXT section - I'll go check after I send this

I tried downloading a compressed u-boot with '-T standalone' and then
saying "bootm 0x200000"  and that doesn't work either.

Is this doable? It should be.  Does anybody know how to do it?

I guess the other thing I "could" do is run expect on the serial port
and set up the paramters that way, but I think the *cascaded u-boot*
idea is better.

-mike wellington
  wellington at lucent.com
  platforms at bithead.com

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