I have intel x86_64 based system I am trying to understand /proc/iomem output. When i see cat /proc/iomem, along with many PCIe and other ranges of system memory i can see following

# cat /proc/iomem | grep -i ram

00001000-0009ffff : System RAM
00100000-cf3d8fff : System RAM
cf56e000-cf7fffff : System RAM
cf800000-cfffffff : RAM buffer
100000000-22dffffff : System RAM
22e000000-22fffffff : RAM buffer

My system has total DDR of 8GB
DDR_Size = 8*1024*1024*1024

Here is some calculation about total DDR memory reported by /proc/iomem

system_RAM_size = (0x0009ffff-0x00001000)+(0xcf3d8fff-0x00100000)+(0xcf7fffff-0xcf56e000)+(0x22dffffff-0x100000000)
RAM_buffer_size = (0xcfffffff-0xcf800000)+(0x22fffffff-0x22e000000)
RAM_Size = system_RAM_size+ RAM_buffer_size

but RAM_Size is not equal to DDR_Size, it is little less,
DDR_Size-RAM_Size=2056198

Would somebody please explain me why is it? Also what is the use of RAM Buffer? why is it separated from System RAM?

Maybe what you want is /proc/meminfo???