Re: are they physical address?

Jim Nelson
2004-10-08T09:49:31Z

Ankit Jain wrote:

>hi
>
>http://www.xml.com/ldd/chapter/book/ch02.html
>
> 00000000-0009fbff : System RAM
> 0009fc00-0009ffff : reserved
> 000a0000-000bffff : Video RAM area
> 000c0000-000c7fff : Video ROM
> 000f0000-000fffff : System ROM
> 00100000-03feffff : System RAM
> 00100000-0022c557 : Kernel code
> 0022c558-0024455f : Kernel data
> 20000000-2fffffff : Intel Corporation 440BX/ZX -
>82443BX/ZX Host bridge
> 68000000-68000fff : Texas Instruments PCI1225
> 68001000-68001fff : Texas Instruments PCI1225 (#2)
> e0000000-e3ffffff : PCI Bus #01
> e4000000-e7ffffff : PCI Bus #01
> e4000000-e4ffffff : ATI Technologies Inc 3D Rage LT
>Pro AGP-133
> e6000000-e6000fff : ATI Technologies Inc 3D Rage LT
>Pro AGP-133
> fffc0000-ffffffff : reserved
>what is it reserved for?
>
>if somebody can explin me this:
>
>"Once again, the values shown are hexadecimal ranges,
>and the string after the colon is the name of the
>"owner" of the I/O region. "
>
>
>

What you are seeing is the remapped I/O space for various components in
your computer. During bootup, the kernel scans the various buses and
identifies various devices. Each driver remaps the I/O space for PCI
devices - they are physical addresses in that those memory addresses do
map to real devices, but they are not real memory addresses.

IIRC, the "reserved" area is the remapped kernel address space - they
set it up to remap to the top of the 32-bit memory address range in
order to allow hard-coded function calls - it is faster to hard-code the
function calls than to maintain symbol tables.

I see this computer is a laptop - now I understand why you are reluctant
to upgrade the RAM.

>thanks
>
>ankit