I've gotten gumstix to boot from a ramdisk to boot from the CF card when I was using 'buildroot' since then we've transitioned to OE(at least partially) and have been using 'mmcboot'.

genext2fs  -N 1000 -b 12000 -d /mnt/loop ramdisk.img ; gzip -f --best ramdisk.img  ; /opt/gumstix-buildroot/build_arm-iwmmxt-linux-gnueabi/u-boot-1.2.0/tools/mkimage -T ramdisk -C gzip -n "rootfs" -d ramdisk.img.gz -A ARM uRamdisk

this is the combination of commands that I used to create the ramdisk(YMMV)...   You might be getting the 'bad magic number' if you didn't process the resulting image with 'mkimage'.

Also here are to boot args I used...

root=/dev/ram0 rw console=ttyS0,115200n8 reboot=cold,hard rdinit=/sbin/initrd

Also, make sure that you have your kernel built with ramdisks built-in.

General setup --->

[*] Initial RAM filesystem and RAM disk (initramfs/initrd) support

Block devices --->

(1) Default number of RAM disks

(4096) Default RAM disk size (kbytes)

(1024) Default RAM disk block size (bytes)

----- Original Message ----
From: Ian Meier <ian.meier@irdinc.com>
To: gumstix-users@lists.sourceforge.net
Sent: Monday, April 21, 2008 7:48:40 PM
Subject: [Gumstix-users] Ramdisk Root Filesystem


Has anyone used a ramdisk-based rootfilesystem with OE?  I've added ex2.gz
to IMAGE_FSTYPES and it generates a compresssed ext2 filesystem image.
However, I haven't figured out the proper bootargs so the kernel will
decompress and mount it.  I just get a "Bad Magic Number" error.  Do I need
to use mkimage to put a U-Boot header on it?  My goal is to store a
compressed ramdisk image in NOR flash, and have the kernel decompress it
into ram and use it as a ramdisk rather than a jffs2 filesystem.

Also, the convention seems to be to load the kernel image to address
a2000000.  What happens to the memory from a000000 to a1ffffff?  Is this
memory available for system RAM? 

Ian Meier
View this message in context: http://www.nabble.com/Ramdisk-Root-Filesystem-tp16818330p16818330.html
Sent from the Gumstix mailing list archive at Nabble.com.

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