how much ram enough to run kernel ?

Hi:

I want to ask how much ram is enough to run kernel? It is said that only bigger than 512K.

If this can realize,but I don't know Microtronix have made some constrain to the ram space or not ?

For example :in the link file ,the ram exec address is what ,I don't know.Because ,in the file drivers\mtd\maps\altera.c ,have many constrain to the ram and flash ,such as size ,location address.

I can do some modify?

Best regards

jigdo