RAM

Memory Detection in Linux happens either through the BIOS INT call or through the EFI. The bios call are mode through the functions detect_memory_e820(),detect_memory_e801() detect_memory_88().   These functions are declared in arch/x86/boot/memory.c.

Either from EFI or through the BIOS INT call the paramaters of the memory will be stored/pointed by boot_params structure. 


Link to know more about the memory detection

1. http://wiki.osdev.org/Detecting_Memory_%28x86%29#BIOS_Function:_INT_0x15.2C_EAX_.3D_0xE820