Panda How to MLO & u-boot
Contents
This is a WIP don't be surprised if nothing below this line is correct.
Introduction
Newer kernels require that you use a recent MLO (x-loader) and u-boot.
You can build these from source, or try to find binaries. One issue with the binary route is that you might want to alter the kernel command line embedded inside u-boot. Such as for experimenting with different partition formats, or different filesystem types (ext3 vs ext2), etc. Of course you could stop the autoboot and type it in yourself, but we will build from source. An even better solution is to use a boot.scr file to send parameters to u-boot, it's easy to create, see below.
For this How-to, we will use the Code Sourcery G++ version arm-2009q3. It should already be installed on your system. Kernels have also been successfully built with arm-2010q1.
MLO
First, let's get the x-loader source code and build it.
git clone git://gitorious.org/pandaboard/x-loader-mainline.git
cd to the x-loader directory
Next, select the panda config:
make CROSS_COMPILE=Path_to_your/arm-2009q3/bin/arm-none-linux-gnueabi- omap4430panda_config
Now compile MLO:
make CROSS_COMPILE=Path_to_your/arm-2009q3/bin/arm-none-linux-gnueabi- ift
This should produce the MLO file in the x-loader directory.
u-boot
Now for U-boot:
git clone git://gitorious.org/pandaboard/u-boot-mainline.git
Next, select the panda config:
make CROSS_COMPILE=Path_to_your/arm-2009q3/bin/arm-none-linux-gnueabi- omap4_panda_config
Change ttyS2 to ttyO2 in the u-boot kernel command line in: u-boot/include/configs/omap4_panda.h
Now compile U-boot:
make USE_PRIVATE_LIBGG=yes CROSS_COMPILE=Path_to_your/arm-2009q3/bin/arm-none-linux-gnueabi-
This should produce u-boot.bin in the u-boot directory
boot.scr
Creating a working SD card
Use this script to prepare an SD card with the small vfat partition and the larger ext2/3 partition (it has been posted many places, I take no credit for it btw, the card needs to be larger than 64Mbytes since this original script wants to make a 64Mbyte vfat partition) You may need to be root for some of the following operations. For the feint of heart, you can use sudo instead in the right places.
#!/bin/sh if [ ! "$1" = "/dev/sda" ] ; then DRIVE=$1 if [ -b "$DRIVE" ] ; then dd if=/dev/zero of=$DRIVE bs=1024 count=1024 SIZE=`fdisk -l $DRIVE | grep Disk | awk '{print $5}'` echo DISK SIZE - $SIZE bytes CYLINDERS=`echo $SIZE/255/63/512 | bc` echo CYLINDERS - $CYLINDERS { echo ,9,0x0C,* echo ,,,- } | sfdisk -D -H 255 -S 63 -C $CYLINDERS $DRIVE mkfs.vfat -F 32 -n "boot" ${DRIVE}1 mke2fs -j -L "rootfs" ${DRIVE}2 fi fi
If you have trouble with the pandaboards ROM CODE not liking your vfat partition check it out with this program.
Thanks go to mru and av500 who have gone a long way to dispell the cargo-cult fokelore surrounding the ROM CODE.
#include <stdio.h> #include <sys/types.h> #include <unistd.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> int main( int argc, char **argv ) { if ( argc < 2 ) { printf("check /dev/sdX you must be root too \n"); return 1; } int fd = open( argv[1], O_RDONLY ); lseek( fd, 0 + 446 + 8, SEEK_SET ); int start; int num_mbr; read( fd, &start, 4 ); read( fd, &num_mbr, 4 ); int num_bpb = 0; lseek( fd, start * 512 + 0x13, SEEK_SET ); read( fd, &num_bpb, 2 ); if( num_bpb == 0 ) { lseek( fd, start * 512 + 0x20, SEEK_SET ); read( fd, &num_bpb, 4 ); } printf( "start: %d mbr: %d bpb: %d -> %s\n", start, num_mbr, num_bpb, num_mbr == num_bpb ? "PASS" : "FAIL!" ); return num_mbr == num_bpb;
Save the above text as sdtest.c and compile it with:
gcc sdtest.c -o sdtest
I run it on the desktop that setup my sd card, if it reports failure then something went wrong with the setup script.
No clue as to how to fix it (yet).