Question : doubt  in Memory map and IO map

Hi all,
         
------>How Memory mapped address is fast than IO mapped address???

------> Is IO mapped address is a physical address???
            (Ex: COM port IO-address is 0x3f8  is it physical address... or  processor bus address which is directly linked to COM port IO???)

Rgds
Madhukar

Answer : doubt  in Memory map and IO map

> Is physical address is different form physical memory(RAM) addrress ??? if so, can u please explain how???
In the context of devices, if devised is memory mapped, then the address of that device is treated as a memory location. In that case there will be no actual memory address refering to a memory location with the same address. e.g. suppose you have 1KB memory and you map devices from memory address 1010 to 1023. Then any instruction which refers to location 1011 refers to that device. The actual memory of 1KB can now be addressed only from 0 to 1009. In effect, physical memory locations 1010 to 1023 are inaccessible.
On the other hand, if device was I/O mapped, you can have a physical device having address 1010 as well as access the physical memory location 1010.

>  my doubt is:   if we see  /proc/ioports ....
> Is the address show are  of physical memory address???
I would refer you to proc man page of your distribution. proc information is not the same across all distributions and even different versions of the same distribution.