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@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 _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
