faq

ARMboot is a firmware monitor/bootloader for embedded systems based on ARM or StrongARM CPUs

QUESTIONS

1. I have built a vmlinux image but I can boot it.

2: The mkimage tool, ARMboot's tftp command, and the bootm command require
   certain load and entry addresses. I'm confused which ones to chose.


ANSWERS



1. I have built a vmlinux image but I can boot it.
--------------------------------------------------

ARMboot is designed to boot Images as created by the mkimage tool, that
comes with ARMboot and is automatically built, too. You cannot directly load
the vmlinux image, as it expects a number of prerequisits such as special
register contents etc.



2. The mkimage tool, ARMboot's tftp command, and the bootm command require
   certain load and entry addresses. I'm confused which ones to chose.
--------------------------------------------------------------------------

Well, there are 3 different addresses:

1. Kernel Load Address. This is the address, where the kernel was linked
   to when you built the vmlinux and can be found in arch/arm/Makefile.
   The default for it is:
   
   ifeq ($(CONFIG_CPU_32),y)
   PROCESSOR    = armv
   TEXTADDR     = 0xC0008000
   LDSCRIPT     = arch/arm/vmlinux-armv.lds.in
   endif
   
   Provide this as "-a" parameter to mkimage.

2. Kernel Entry Point. This is the address, where ARMboot jumps to to
   enter the Kernel. It usually is the same as the kernel load address.

   Provide this as "-e" parameter to mkimage.

3. The Network Download Address. This is where you download the mkimage
   File. This address MUST BE different to the Kernel Load Address, and
   should be sufficiently far away to allow ARMboot to relocate the 
   image to the final Kernel Load Address. Loading to the 5th MB
   within the RAM is usually a good idea, eg. if the RAM begins at
   0xc0000000, you can do this:
   
   LART # tftp c0400000 linux.img
   ARP broadcast 1
   eth addr: 00:02:03:04:05:06
   TFTP from server 192.168.1.1; our IP address is 192.168.1.2
   Filename 'image.img'.
   Load address: 0xc0400000
   Loading: 
   ##################################################################done
   Bytes transferred = 567252 (8a7d4 hex)
   LART # bootm c0400000
      Image Name:   Linux 2.4.18
      Created:      Mon Jun 24 12:00:01 2002
      Image Type:   ARM Linux Kernel Image (gzip compressed)
      Data Size:    567188 Bytes = 553 kB = 0 MB
      Load Address: 0xc0008000
      Entry Point:  0xc0008000
      Verifying Checksum ... OK
      Loading Kernel Image ... OK	 

   Starting kernel ...
   Linux version 2.4.18 (mag@mag) (gcc version 2.95.3 20010315 (release)) #4 Mon Jun 17 20:35:32 CST 2002
   ...

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