[Syllable-kernel] preparing for 64-bit in the kernel (correction)

[Jake H. <jh...@po...>]

As a correction to my last post, a 40-bit linear address can support up 
to 1TB, not 1024TB, of RAM.  At OEMPCworld.com, a 2.0GB PC2-3200 
(400MHz) DDR 2 ECC DIMM costs $499.85.  If your server had 512 DIMM 
sockets to put them in, you could buy 1TB of RAM for your server for 
around US$256,000 and you've just maxed out your memory.

Correcting the other numbers:  with 48 bits, x86-64 can address up to 
256TB of virtual address space.

The DEC Alpha with 8K pages can handle up to 8TB of virtual address 
space and 32TB of physical memory.  By expanding the page size up to 
64K, the architecture can support up to 32768 TB of virtual address 
space and 256TB of RAM.  I don't know what the limits are for PPC or 
Itanium.

-Jake