Configuring u-boot-xlnx for NFS and TFTP.

It seems that the version of analogdevicesinc/u-boot-xlnx (90401ce) linked from analogdevicesinc/m2k-fw master (d0b6016) doesn't have an option for USB_ETHER.

I've tried the current master alogdevicesinc/u-boot-xlnx  (f06dec3)  which does have an option for USB_ETHER. However, it doesn't have ./configs/zynq_m2k_defconfig.

I've tried using the  ./configs/zynq_m2k_defconfig from the older u-boot-xlnx but run into difficulties, maybe because the old defconfig is incompatible. Specifically, the make error I'm getting is:

.config:146:warning: symbol value '' invalid for SYS_TEXT_BASE
*
* Restart config...
*
*
* Boot images
*
Enable support for Android Boot Images (ANDROID_BOOT_IMAGE) [N/y/?] n
Support Flattened Image Tree (FIT) [Y/n/?] y
Support SHA256 checksum of FIT image contents (FIT_ENABLE_SHA256_SUPPORT) [Y/n/?] y
Enable signature verification of FIT uImages (FIT_SIGNATURE) [Y/n/?] y
Show verbose messages when FIT images fail (FIT_VERBOSE) [Y/n/?] y
Select the best match for the kernel device tree (FIT_BEST_MATCH) [N/y/?] n
Support Flattened Image Tree within SPL (SPL_FIT) [N/y] n
Enable signature verification of FIT firmware within SPL (SPL_FIT_SIGNATURE) [N/y] n
Enable SPL loading U-Boot as a FIT (SPL_LOAD_FIT) [N/y/?] n
Set up board-specific details in device tree before boot (OF_BOARD_SETUP) [N/y/?] n
Set up system-specific details in device tree before boot (OF_SYSTEM_SETUP) [N/y/?] n
Update the device-tree stdout alias from U-Boot (OF_STDOUT_VIA_ALIAS) [N/y/?] n
Extra Options (DEPRECATED) (SYS_EXTRA_OPTIONS) []
Text Base (SYS_TEXT_BASE) [] (NEW) aborted!

Console input/output is redirected. Run 'make oldconfig' to update configuration.

I've tried adding a sensible value for SYS_TEXT_BASE using menuconfig but this gets lost in the resulting .config 

# CONFIG_ARCH_ASPEED is not set
CONFIG_SYS_TEXT_BASE=
# CONFIG_SPL_GPIO_SUPPORT is not set

Can anyone help please.

DrFlute1