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i.mx6 sabre sdp ramdisk root file system problem

Question asked by jongjin yi on Jan 6, 2014
Latest reply on Jan 8, 2014 by Alex Yang

I'm working on imx6s sabre sdp and trying to boot with ramdisk root file system, but it's not working.

With i.mx51, ramdisk root file system boot was successful with almost same configuarion.

Could somebody tell me what I missed?


Here is what have i done.


1. kernel config.

at kernel menuconfig, i've selected following configuration

General setup > initial ram filesystem and ram disk support


Device drivers > block devices > ram block device support



2. ramdisk creation

I made ramdisk image with rootfs created by ltib

dd if=/dev/zero of=ramdisk bs=1k count=131072  ==> 128MB ramdisk
mkfs.ext2 ramdisk
mount -t ext2 -o loop ramdisk /mnt/rootfs
cp -a ./ltib/rootfs/* /mnt/rootfs
umount dir_ramdisk
gzip ramdisk  ==> which create ramdisk.gz


3. ramdisk deployment

I placed u-boot, uImage, ramdisk.gz on SD slot 3 SD card,

0~1M : u-boot area

1M~5M : kernel area

5M~55M : ramdisk.gz area

with the following commend on linux host computer. (sdcard is recognized as /dev/sdc in my linux host)

dd if=u-boot of=/dev/sdc bs=512 seek=2 skip=2 conv=fsync

dd if=uImage of=/dev/sdc bs=512 seek=2048 conv=fsync

dd if=ramdisk.gz of=/dev/sdc bs=512 seek=10240 conv=fsync


4. kernel cmdline configuration at u-boot command

the following is what I entered at u-boot command line.

set bootargs console=ttymxc0,115200 nosmp video=mxcfb0:dev=ldb,LDB-XGA,if=RGB666 ldb=sin1 ip= initrd=0x10c00000,50M root=/dev/ram0 ramdisk_size=131072

mmc dev 2

mmc read 0x10800000 0x800 0x2000  ==> read 4Mbyte from 1M offset. kernel

mmc read 0x10c00000 0x2800 0x19000 ==> read 50Mbyte from 5M offset, ramdisk.gz



and then, kernel booting halted with the following message

mmcblk1: mmc2:b02c SD04G 3.69 GiB

mmcblk1: p1

PHY: 1:01 - Link is Up - 100/Full

IP-Config: Guessing netmask

IP-Config: Complete:

     device=eth0, addr=, mask=, gw=,

     host=, domain=, nis-domain=(none),

     bootserver=, rootserver=, rootpath=

RAMDISK: Couldn't find valid RAM disk image starting at 0.

List of all partitions:

1f00            1024 mtdblock0  (driver?)

1f01            3072 mtdblock1  (driver?)

b300         7757824 mmcblk0  driver: mmcblk

b310            2048 mmcblk0boot1  (driver?)

b308            2048 mmcblk0boot0  (driver?)

b318         3872256 mmcblk1  driver: mmcblk

  b319         3814912 mmcblk1p1 00000000-0000-0000-0000-000000000000

No filesystem could mount root, tried:  ext3 ext2 ext4 cramfs vfat msdos

Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(1,0)

[<8004a834>] (unwind_backtrace+0x0/0xf8) from [<8050c514>] (panic+0x74/0x18c)

[<8050c514>] (panic+0x74/0x18c) from [<80008dac>] (mount_block_root+0x1e0/0x224)

[<80008dac>] (mount_block_root+0x1e0/0x224) from [<80008fc4>] (mount_root+0xe8/0x108)

[<80008fc4>] (mount_root+0xe8/0x108) from [<80009148>] (prepare_namespace+0x164/0x1bc)

[<80009148>] (prepare_namespace+0x164/0x1bc) from [<80008a04>] (kernel_init+0x108/0x13c)

[<80008a04>] (kernel_init+0x108/0x13c) from [<80044aa4>] (kernel_thread_exit+0x0/0x8)