As you know there are many configuration file for arm boards under l4re/mk/platforms folder. When we open one of them, vexpress, it contains the following information:

PLATFORM_NAME        = "ARM Versatile Express"
PLATFORM_ARCH        = arm
PLATFORM_RAM_BASE    = 0x60000000
PLATFORM_RAM_SIZE_MB = 256

The interesting part here is the size of the RAM, because you cannot give same size of the RAM when you compile the l4 lua configuration. In case you give l4linux raises "memory cannot reach out of the ..." error. what is the exact reason of that? is there any specific point where the ram size of arm boards are static defined? 

Thanks in advance,