Showing posts with label mmc. Show all posts
Showing posts with label mmc. Show all posts

Wednesday, October 15, 2008

Booting Linux from SD card on my Beagle

It was the day when i started my battle to bring up Linux on my Beagle from SD card . After a long struggle , i learnt two things
* For my Kernel , MMC and SD cards are different .
* SD fs should be built with ROOT user .

The MMC/SD card can be partitioned using gparted .
Partition 1 : VFAT , flag =boot (uImage , MLO)
Partition 2: EXT-2 (file system)

The uboot ENV params are here :
setenv bootcmd 'mmcinit;fatload mmc 0 0x80300000 uImage;bootm 0x80300000';
setenv bootargs console=ttyS2,115200n8 noinitrd root=/dev/mmcblk0p2 rootfstype=ext2 rw rootdelay=1 nohz=off

Some tips on RAMDISK ...

# on the linux host
mkdir workspace
cd workspace
gzip -cd /rd.ext2-bin > ramdisk.orig
mkdir mountpoint
mount -o loop ..../workspace/ramdisk.orig ..../workspace/mountpoint
# should see all the files, etc. in "mountpoint" subdirectory
# you can make your changes there - or clone the filesytem and
# modify the clone

# then copy somewhere...
mkdir newFs
tar cf - -C mountpount . | tar xvf - -C newFs
umount mountpoint ;# unmount the old image
# then make whatever changes are wanted in 'newFs'
mkdir newFs/home/user ....
// whatever

# tar it up so we can do this more easily next time
tar zcf ramFileSystem.tgz --C newFs .

# then reverse the steps
mkdir -p newFsMountPoint
dd if=/dev/zero of=newRamDiskImage bs=8M count=1 ;# create the file
mkfs.ext2 newRamDiskImage
mount -o loop newRamDiskImage .../newFsMountPoint
tar zxf ramFileSystem.tgz -C ../newFsMountPoint

# finally, unmount and zip
umount .../newFsMountPoint
gzip -c newFsMountPoint myNewRd-ext2.bin
... then copy the file to the SD card
[http://groups.google.com/group/beagleboard/browse_thread/thread/16dc0686c1a78420]