I had a great problem with linux e ppc.

I have a PowerPc Motorola, I install on it a kernel image (2.6.10) that
use a ramdisk as root filesystem.
The original version issued with kernel 2.6.10 is working even if I
recompile it.

Now I want to modify the original ramdisk to insert some file that I
need. If I insert in the ramdisk some little file the kernel continue
to start, but if i insert a great file (4 Mb) the kernel don't boot.
the result on video is:

loaded at: 01864400 0253356C
relocated to: 00400000 010CF16C
board data at: 010CD124 010CD16C
relocated to: 00405238 00405280
zimage at: 00405A05 005BA5C2
initrd at: 005BB000 010CC420
avail ram: 010D0000 AACC8A8B

Linux/PPC load: console=ttyS0,9600 root=/dev/ram0 ramdisk_size=64000
Uncompressing Linux...done.
Now booting the kernel

At this point the system is stopped.
The next line describe what I do to modify the ramdisk and to compile
the kernel.

Mounting ramdisk:

gunzip /usr/src/linux-2.6.10.rm02/arch/ppc/boot/images/ramdisk.image.gz
losetup /dev/loop0
mount /dev/loop0 /opt/commcpu/CommEnvironment/ -o loop -t ext2

Unmounting ramdisk:
umount /opt/commcpu/CommEnvironment/
losetup -d /dev/loop0
fsck /usr/src/linux-2.6.10.rm02/arch/ppc/boot/images/ramdisk.image
gzip -9 /usr/src/linux-2.6.10.rm02/arch/ppc/boot/images/ramdisk.image

Compiling kernel:

cd /usr/src/linux-2.6.10.rm02/
export ARCH=ppc
export CROSS_COMPILE=ppc-
make zImage.initrd