[U-Boot] Loading a userland file

[Grant]

I'm trying to get Tiny Core working on the Beaglebone.  I'm stuck on
getting the Tiny Core userland file "uCore" to load so init works.  I'm
using this uEnv.txt:

bootfile=/uImage
optargs=init=/init rootwait
fatload mmc 0 0x43100000 uCore
mmcboot=echo Booting from mmc ...; run mmcargs; bootm 0x80200000 0x43100000

I get the following "data abort":

## Booting kernel from Legacy Image at 80200000 ...
Image Name:   Linux-3.6.0-rc7-00219-g35e0f42
Image Type:   ARM Linux Kernel Image (uncompressed)
Data Size:    2878667 Bytes = 2.7 MiB
Load Address: 80008000
Entry Point:  80008000
Verifying Checksum ... OK
data abort
pc : [<8ff99480>]          lr : [<8ff996ac>]
sp : 8fe6abd0  ip : 8fe6d163     fp : 00000001
r10: 00000002  r9 : 00000000     r8 : 8fe6af68
r7 : 8ffbaebc  r6 : 43100000     r5 : 8ffbaec0  r4 : 43100000
r3 : 00000000  r2 : 00000010     r1 : 00000000  r0 : 43100000
Flags: nZCv  IRQs off  FIQs on  Mode SVC_32
Resetting CPU ...

If I change mmcboot to:

mmcboot=echo Booting from mmc ...; run mmcargs; bootm 0x80200000

The kernel loads, but init fails:

EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
devtmpfs: error mounting -2
Freeing init memory: 144K
Failed to execute /init.  Attempting defaults...
Kernel panic - not syncing: No init found.  Try passing init= option to
kernel.

Can anyone tell me how to load uCore so init works?

- Grant