🚀 go-pugleaf

Andre' Zehl (crusoe@cs.tu-berlin.de) wrote:
: I'm working on a preparation on the HP-PA RISC Architecture.I'm desparately
: trying to figure out, how you administer the virtual to physical address
: translation. 
... 
: The physical page number (ppn) is identical with the index from the
:hashtable. But this only makes sense, if it's not the virtual page number (vpn)
: which is hashed, but the physical page number, coming out of the
: hardware translation? IS THIS SO ? Is the PDIR Index of the hashtable vpn 
the VPN is hashed.
: the hashed ppn or the hashed ?

Each entry in the hash table points to the FIRST PPN in a linked list of all
physical pages whose VPN hash to the same value.  Thus, you walk
the linked list in the PDIR, examining each entry to see if its VPN matches
the one you are looking for (presumably, the one you got a TLB miss on).
If a match is found, you found it! (And the physical address is
the PPN (which is based on the PDIR index as you noticed) plus the original
bottom 11 or so bits (i.e.: virtual pages are aligned on physical page
boundaries).

(I emailed a little more to him)

--
Stan Sieler
sieler@allegro.com