[U-Boot] SDRAM

[Naitik Amin]

I am using Altera SOC, under my includes, I have a file called 
/include/configs/socfpga_common.h

In this file, I have #define as below.
#define PHYS_SDRAM_1_SIZE               0x20000000

If this #define is set to 0x20000000, and uboot is compiled and loaded, 
the system when boots up into Linux, issuing free command under linux 
shows 512 MB. Which is *correct*. If I change that #define to 0x40000000, 
upon executing free command, linux shows 1G.

My questions, is how does this info from uboot reach kernel ?

Thanks,