[Linux-ia64] what about SGI IA64 io address map

[Barry Wu <wuqb@nudt.edu.cn>]

Hi, all, I am new to Intel Itanium. I do not know
if io address is special linux. For example, in mips
io virtual  address can be converted directly to
physics address by K1seg. I read Itanium system 
architecture and find that all virtual address have
to pass TLB transation. Am I right?

I read include/asm-ia64/sn/sn2/addrs.h and find
that SGI IA64 address is composed of
node-id  +  node offset
If all virtual address have to convert by TLB, then
I think SGI Itanium virtual address have to use
TR register. But Itanium only has 48 DTR and if
we use node-id as part of physics address, then 
each node we have to use a DTR, then SGI IA64 system
have no too DTR to convert this address. The efficiency
must be slow for IO address. I do not know if it is
correct. If someone knows, please give me a reply.

Thanks in advance!

Barry