booting linux

[Vanalme Filip]

My barebox porting on i.MX27 comes in a next phase : booting the kernel. 
I'm using a kernel image from some time ago, an image that worked with redboot (formerly installed bootloader of the board).
I loaded the image to nand-flash :
barebox:/ erase /dev/nand0.kernel.bb
barebox:/ tftp zImage /dev/nand0.kernel.bb
error frame: 0xa7b058f8 0x00000882    <===== ???
TFTP from server 10.0.48.80 ('zImage' -> '/dev/nand0.kernel.bb')
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barebox:/

Apart from the "error frame" message, the transfer seems to be successful.

Then I do :

barebox:/ bootz /dev/nand0.kernel.bb
loaded zImage from /dev/nand0.kernel.bb with size 1777792
commandline: console=ttymxc0,115200 ip=dhcp root=/dev/mtdblock7 rootfstype=jffs2 mtdparts=mxc_nand:256k(barebox)ro,128k(bareboxenv),5M(kernel),-(root)
arch_number: 1802
Uncompressing Linux........................................................................................................................... done, booting the kernel.

The kernel uncompresses but never starts. Any idea why not ? Does barebox expand the kernel to the right place in SDRAM or do I have to specify that in the bootz command ?
I think the kernel is never started at all because I don't see any output at all. In this phase, even having a kernel crash would be great... because at least then I would know the kernel has been running for a while... ;-) 

I guess the image is OK because it uncompresses successfully. Maybe a problem in the bootargs that are passed to the kernel ?
Should I already have a /dev/mtdblock7 device in barebox's /dev ?

Maybe useful information :

barebox:/ printenv
locals:
machine=imx27pdk
ip=dhcp
kernel_loc=nand
rootfs_loc=nand
rootfs_type=jffs2
rootfsimage=root-jffs2
kernelimage_type=zimage
kernelimage=zImage-imx27pdk
nfsroot=:/path/to/nfs/root
autoboot_timeout=3
bootargs=console=ttymxc0,115200
nand_parts=256k(barebox)ro,128k(bareboxenv),5M(kernel),-(root)
rootfs_mtdblock_nand=7
PS1=\e[1;32mbarebox@\e[1;31m\h:\w\e[0m
bootfile=zImage
nameserver=10.0.0.44
domainname=televic.com
globals:
PATH=/env/bin
barebox:/

Filip