DasUBoot

Get the source

  

The u-boot source is now include in the nios2 linux tar ball as described in the wiki InstallNios2Linux.

> cd u-boot
> git fetch
> git branch -a
* nios2
  origin/HEAD
  origin/de2
  origin/master
  origin/neek_c3
  origin/nios2

Check out the branch that contains your board. ie, de2 branch for DE2, neek-c3 for NEEK, nios2 otherwise.

For example, to build for the de2 board,

git checkout -b de2 origin/de2

Compile

To compile run:

make distclean
make <board>_config
make

where <board> should be replaced with the board you want to compile for (e.g. make EP1C20_config will compile for the EP1C20 board). You can see which boards are supported in the board/altera folder.

Test, store in flash

To test, just load u-boot with nios2-download -g u-boot
See manual for fun stuff to do. 

To write to flash:

protect off 0 1ffff
erase 0 1ffff 
tftp 5000000 u-boot.bin
cp.b 5000000 0 $filesize

In this example, flash starts at address 0 and the file u-boot.bin is stored temporarily at 500_0000 which is in sdram (this is for the EP2C35 board)

Starting uClinux from u-boot:

Find your uncompressed version of your uClinux kernel (vmlinux) and run the following commands:
nios2-elf-objcopy -O binary vmlinux vmlinux.bin
gzip -9 vmlinux.bin       # Creates vmlinux.bin.gz
mkimage -A nios2 -O linux -T kernel -C none -a 0x4500000 -e 0x4500000 -n "Insert your name here" -d vmlinux.bin.gz vmlinux.img

where 0x450_0000 is the address you want the image to load too (again, 450_0000 is in the sdram for EP2C35 board). In my setup, I can find vmlinux.bin.gz under uClinux-dist/linux-2.6.x/arch/nios2nommu/boot/compressed/, so that I can skip the two first steps. The mkimage program is found under the tools folder of the u-boot source code. You might have to adjust some Makefiles to compile it.

In u-boot, tftp the image and bootm it:
tftp 5000000 vmlinux.img
bootm 5000000

Board not supported?

At the time of writing, only three boards are supported. If you&apos;re not among the lucky ones, you can start by modifying one of the existing boards (I will use EP1C20 as an example) to make it run on your board:

1. Modify include/configs/EP1C20.h to make it reflect the setup in your system. You should be able to find all the addresses you need from your .ptf file, but it might be easier to look some of it up in your Quartus project.
   
2. Modify board/altera/ep1c20/config.mk and update TEXT_BASE to reflect your system. This should normally be the end of your sdram - 256k (e.g. EP2C35 sdram start at 0x400_0000 and has length 0x200_0000 = 0x600_0000, subtract 0x4_0000 (256k) = 0x5fc0000). This is were u-boot will be placed.
3. Either find and use an appropriate flash.c file, or just modify flash_init to return a non-zero value without probing the actual flash. If you choose to modify, your flash utilities won&apos;t work. But you&apos;ll have everything else ;-) For EP2C35, read the following post: http://forum.niosforum.com/forum/lof...php/t4194.html 
4. Compile

Once you get this working, you can do a real port (not covered here - yet).

Various bits and pieces