[U-Boot] using initrd with U-boot on the imx28evk
Marek Vasut
marex at denx.de
Mon Sep 17 23:31:05 CEST 2012
Dear Bill,
I'm CCing Fabio ... he might have some idea for you.
> Marek,
>
> Yes, I checked the kernel and it is enabled for ramdisk support in
> Linux, gzip compression, and loop back block driver. I did find some
> other posts where some folks added the address of the ram drive. So I
> changed the kernel arguments from:
>
> setenv bootargs console=ttyAM0,115200n8 debug root=/dev/ram rw ip=dhcp
> fec_mac= TO:
>
> setenv bootargs console=ttyAM0,115200n8 debug root=/dev/ram rw
> initrd=0x43000000,40K ip=dhcp fec_mac=
>
>
> And now the kernel output generates a additional error line from RAMDISK:
>
> ...
> ...
> ...
> RAMDISK: Couldn't find valid RAM disk image starting at 0. <<<<<<<< This
> line now appears on the console
> 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)
> ...
> ...
> ...
>
>
> Is it something with the RAM disk format or the uboot tool mkimage
> parameters?
>
> Thanks,
> Bill
>
> On 9/12/2012 6:44 PM, Marek Vasut wrote:
> > Dear Bill,
> >
> >> 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 at 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?
> >
> > Some ancient kernel you have ... did you enable ramdisk support in Linux?
> > And gzip compression for it ? And loop back block driver ?
> >
> >>>> Thanks,
> >>>> Bill
> >>>
> >>> Best regards,
> >>> Marek Vasut
> >
> > Best regards,
> > Marek Vasut
More information about the U-Boot
mailing list