I was looking into the "/proc/iomem" entries and have a doubt regarding the same.
My Linux PC is running a Intel Xeon and has a system RAM of 4GB.
/proc/iomem entry of my system looks like
00000000-0000ffff : reserved 00010000-0009f3ff : System RAM 0009f400-0009ffff : reserved 000a0000-000bffff : PCI Bus 0000:00 000c0000-000c7fff : Video ROM 000ca000-000cbfff : reserved 000ca000-000cafff : Adapter ROM 000cb000-000cbfff : Adapter ROM 000cc000-000cffff : PCI Bus 0000:00 000d0000-000d3fff : PCI Bus 0000:00 000d4000-000d7fff : PCI Bus 0000:00 000d8000-000dbfff : PCI Bus 0000:00 000dc000-000fffff : reserved 000f0000-000fffff : System ROM 00100000-7fedffff : System RAM 01000000-01520fa4 : Kernel code 01520fa5-01c0e44f : Kernel data 01d56000-0201d963 : Kernel bss 03000000-0b0fffff : Crash kernel 7fee0000-7fefefff : ACPI Tables 7feff000-7fefffff : ACPI Non-volatile Storage 7ff00000-7fffffff : System RAM c0000000-febfffff : PCI Bus 0000:00 fec00000-fec0ffff : reserved fec00000-fec003ff : IOAPIC 0 fed00000-fed003ff : HPET 0 fed00000-fed003ff : pnp 00:08 fee00000-fee00fff : Local APIC fee00000-fee00fff : reserved fffe0000-ffffffff : reserved
Now, assuming that my processor has 32 address lines ( i feel that it has 40 address lines - i see this from /proc/cpuinfo), this means that my processor will be able to address 4GB of physical memory.
Looking from my "/proc/iomem" entries, I see that only 2GB of system RAM is being directly addressed by my CPU.
Now my doubt is
- How does my CPU addresses other 2 GB of RAM ? Where can I see the memory mapping for that ?