[U-Boot] Specifying flash page sizes

Hi

I have been using uboot to with a number of devices which have a 256 byte page. Currently I'm using a device with a 512 byte page. I have had problems getting Linux to run on my system, the initial problem was caused by the flash drivers in linux specifying a page of 256 bytes and not 512. I am still having numerous issues with Linux, and I'm wondering whether it is because the kernel flash images are not being programmed correctly? Ho do I specify the flash page size in uboot source code? I've not been able to find how to do that.

Kind regards

Andrew