I'm using U-boot version: U-Boot 2012.07
Through googling, I've come across several variations of using a
ramdisk. So I selected some things that looked good. So basically, I
am building a rootfs as a ramdisk by:
dd if=/dev/zero of=./myinitrd.img bs=1M count=35
mke2fs -m 1 ./myinitrd.img
mkdir ./myinitrd
mount -t ext2 ./myinitrd.img ./myinitrd -o loop
cp -r rootfs/* ./myinitrd/.
umount ./myinitrd/
gzip ./myinitrd.img
rm -rf myinitrd
Then I use the u-boot tool to prepare it for use with u-boot by:
u-boot-imx/tools/mkimage -n 'MyRamDisk' -A arm -O linux -T
ramdisk -C none -d ./myinitrd.img.gz rootfs-initrd
I place both both my uImage and rootfs-initrd on a USB stick and insert
it into the imx28evk and enter u-boot command line. I then do:
usb start
fatload usb 0 0x42000000 uimage
fatload usb 0 0x43000000 rootfs-initrd
setenv bootargs console=ttyAM0,115200n8 debug root=/dev/ram rw
ip=dhcp fec_mac=
bootm 0x42000000 0x43000000
u-boot then starts booting with:
## Booting kernel from Legacy Image at 42000000 ...
Image Name: Linux-2.6.35.3-571-gcca29a0-g45b
Created: 2012-09-08 22:31:46 UTC
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 2582304 Bytes = 2.5 MiB
Load Address: 40008000
Entry Point: 40008000
Verifying Checksum ... OK
## Loading init Ramdisk from Legacy Image at 43000000 ...
Image Name: MyRamDisk
Created: 2012-09-12 20:51:35 UTC
Image Type: ARM Linux RAMDisk Image (uncompressed)
Data Size: 37774 Bytes = 36.9 KiB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
Loading Kernel Image ... OK
OK
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
Linux version 2.6.35.3-571-gcca29a0-g45b53d0-dirty (blsousan@ubuntu)
(gcc version 4.4.4 (4.4.4_09.06.2010) ) #13 PREEMPT Sat Sep 8 14:06:34
PDT 2012
CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00053177
CPU: VIVT data cache, VIVT instruction cache
Machine: Freescale MX28EVK board
....
....
....
The kernel starts to boot, I get all the kernel output, and at the end
it does not find the rootfs. I get:
...
...
...
List of all partitions:
b300 3872256 mmcblk0 driver: mmcblk
b301 1024 mmcblk0p1
0800 503808 sda driver: sd
0801 503792 sda1
No filesystem could mount root, tried: ext3 ext2 vfat msdos iso9660
Kernel panic - not syncing: VFS: Unable to mount root fs on
unknown-block(1,0)
Backtrace:
I not sure how the kernel knows where the ramdisk lives in memory (
0x43000000) where the the uboot put it ?
Thanks,
Bill
On 9/12/2012 5:29 PM, Marek Vasut wrote:
Dear Bill,
Has anyone used U-boot on the imx28evk with initrd to setup a small
rootfs in RAM? I need the ability to do have a small temp rootfs to
assist in mounting a full rootfs from a USB for field upgrade purposes.
Yes, it's a linux thingie though. What's the problem? What version of uboot do
you use?
Thanks,
Bill
Best regards,
Marek Vasut
--
William (Bill) L. Sousan, Ph.D.
(w) 402.331.4977 ext. 4002
bsou...@techsi.com
Technical Support Inc.
11253 John Galt Blvd
Omaha, NE 68137
www.techsi.com
8(a) SDB Certified, ISO 9001:2008
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