The code in vtophys is for the simulator to be able to translate a
virtual address to a physical one for whatever purpose. It manually
walks the page table and figures out what the address should be
returning it whatever asked(for example overwriting a value in
memory, or reading an in-kernel structure during execution to figure
out what thread is currently scheduled). It is not called during the
normal translation process for a tlb miss. Alpha has a software
filled TLB (not a HW filled one) so the palcode entry point for a tlb
miss (e.g. dtb_miss_single) executes instructions to walk the page
table and fill the tlb.
Ali
On Feb 12, 2007, at 11:17 AM, [EMAIL PROTECTED] wrote:
Hi Ali,
Thank you for your patience.
I have read the section II-B of alpha architecture handbook. I
know alpha
uses multilevel Page Table structure.
As you said, on a TLB miss the PAL code searches the page table
for the
missing entry. I found the multilevel page table lookup function is
implemented in vtophys.cc(AlphaISA::kernel_pte_lookup()). But on a TLB
miss, this function is not called. So I am confused about how the PAL
code gets the appropriate entry?
Thanks.
Tracy
Briefly, on a TLB miss the PAL code searches the page table for the
missing entry, when it finds the appropriate entry it writes to an
Internal Processor Register (IPR) that causes the entry to be
inserted into the TLB. Section II-B Chapter 3 of the Alpha
Architecture Handbook provides the particular details of the process.
Ali
On Feb 5, 2007, at 3:27 PM, [EMAIL PROTECTED] wrote:
Hi,
Now I am trying to add some new virtual to physical address
translation
algorithm in full system.I know this functionality is done in
tlb.cc,
but I don't know how the TLB is build up, which means how TLB
entries
are added into the table?
I find AlphaRegFile::MiscRegFile::setIpr() is called to insert a
new
entry. Can anyone explain this process for me?
Thank you very much.
Tracy
translate() in tlb.cc implements an alpha like TLB. So it does
virtual to physical translation for the guest.
vtophys() converts a virtual address for the guest into a virtual
address for the host.
Ali
On Jan 22, 2007, at 2:26 PM, [EMAIL PROTECTED] wrote:
Hi all,
I find two virtual to physical address translation
functions in
M5:
One is translate() defined in AlphaITB/AlphaDTB class in
tlb.cc,
the other one is vtophys() defined in vtophys.cc.
Does anyone know which one is for simulated virtual address to
simulated physical address translation? And which on is for
simulated
virutal address to host physical address translation?
Thanks!
Tracy
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