[meta-xilinx] Problems booting from SD card

[Edward Wingate]

I am booting a custom zynq board from a SD card.
uEnv.txt contains this:
kernel_image=uImage
devicetree_image=my-board.dtb
ramdisk_image=my-image-my-board.cpio.gz.u-boot

These files are all also on the SD card.

On bootup I get this:
U-Boot 2015.01 (May 13 2015 - 10:34:29)

Board:  Xilinx Zynq
I2C:   ready
DRAM:  ECC disabled 512 MiB
MMC:   zynq_sdhci: 0
SF: Detected S25FL512S_256K with page size 512 Bytes, erase size 256
KiB, total 128 MiB
*** Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Board:  Xilinx Zynq
Net:   Gem.e000b000
reading uEnv.txt
112 bytes read in 11 ms (9.8 KiB/s)
Importing environment from SD ...
Hit any key to stop autoboot:  0
Device: zynq_sdhci
Manufacturer ID: 27
OEM: 5048
Name: SD8GB
Tran Speed: 50000000
Rd Block Len: 512
SD version 3.0
High Capacity: Yes
Capacity: 7.4 GiB
Bus Width: 4-bit
reading uEnv.txt
112 bytes read in 11 ms (9.8 KiB/s)
Loaded environment from uEnv.txt
Importing environment from SD ...
Copying Linux from SD to RAM...
reading uImage
 **Unable to read file uImage
zynq-uboot>

It seems to be unable to read kernel file uImage.
The sdboot environment variable is:

sdboot=if mmcinfo; then run uenvboot; echo Copying Linux from SD to
RAM... && load mmc 0 ${kernel_load_address} ${kernel_image} && load
mmc 0 ${devicetree_load_address} ${devicetree_image} && load mmc 0
${ramdisk_load_address} ${ramdisk_image} && bootm
${kernel_load_address} ${ramdisk_load_address}
${devicetree_load_address}; fi

But if I run each load and bootm statement individually at the u-boot
prompt, everything works and Linux boots:

zynq-uboot> load mmc 0 0x2080000 uImage
zynq-uboot> load mmc 0 0x2000000 my-board.dtb
zynq-uboot> load mmc 0 0x4000000 my-image-my-board.cpio.gz.u-boot
zynq-uboot> bootm 0x2080000 0x4000000 0x2000000

[Successfully boots Linux]

I did verify all the enrivonment variables for image names and load
addresses are correct. It's curious things work if entered
individually at the prompt, but booting from SD card (and "run
sdboot") fails.

 Anyone know what I can try next to fix/debug this?   Thanks for your help.