what about SGI IA64 io address map

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