DP - Display Page Directory and Table Entries

Display entries from the page tables of the default thread slot. See the .S command for information on changing the default thread slot.

Syntax:

───┬─  DP   ──┬──┬─────────────────┬──────────────────────────
     └─  DPD  ──┘  └─ addr ─┬──────┬─┘
         DPA                └─ Ln ─┘

Parameters:

A

Display both page table and page directory entries. This is the default.
D
Display only page directory entries.
addr
The linear or virtual address whose page directory and table entries are to be displayed. If not specified DP displays the entire page directory and its page tables.

An address expression may be specified.

Ln
The number of page table entries to display starting with the entry for addr. The default is to display the all page table entries from this entry assigned to addr.

Note: Due to a bug in some versions of the Kernel Debugger an extra zero is required for this parameter.

Results & Notes:

One or more page and directory table entries are displayed. An example display follows:

────────────────────────────────────────────────────────────────────────DP %90000 L50

 linaddr   frame   pteframe  state res Dc Au CD WT Us rW Pn state
%00090000* 012f3  frame=012f3  2    0  D  A        U  W  P  resident
%00090000         vp id=00a76  0    0  c  u        U  W  n  pageable
%000a0000  000b8  vp id=000b8  1    0  D  u        U  W  n  uvirt
%000b0000  00888  frame=00888  0    0  D  A        U  W  P  pageable
%000c0000         vp id=00b8f  0    0  c  u        U  W  n  pageable
%000d0000         vp id=00b92  0    0  c  u        U  W  n  pageable
##
────────────────────────────────────────────────────────────────────────

Output from the DP command is presented in tabular form. Each of the columns shown is described as follows:

linaddr

Linear address of virtual memory whose page directory and table entries are being formatted. Those lines corresponding to directory entries have an * flag suffixed to the linear address. Page table entries for a given directory entry are formatted following the directory entry.

In the example above linear address %90000 has its page table located in physical frame 12f3, that is at physical %%12f3000. The page table entry corresponding to virtual memory at %90000 is described in the second line. Each of the following lines are consecutive entries from page table 12f3.

frame
The real storage frame number that contains either the page table (* suffix to linaddr) or page frame corresponding to the linaddr. If this field is blank then the frame has been discarded. If it contains a frame number then the contents are still valid even though the page table entry no longer points to a page frame. See pteframe field for further discussion.
pteframe
For table entries with the present bit set the this field shows the page frame number pointed to by this table entry. This is shown as frame=fffff. Use the frame number with the .MP command to obtain information on allocation and ownsership of this this frame of real storage.

For decommitted pages the table entry contains the Virtual Page ID. This is shown as vp id=vvvvv. Use the .MV command with the virtual page Id to obtain information on allocation and ownership of this memory.

Notes

The vp id is not valid to use with .MV if the state of the table entry is uvirt.

If the frame has been decommitted but the frame field still shows a frame number then the frame contents are still valid for reclaiming without a page-in operation from the swap file. The corresponding virtual page will be queued from the idle list. See .MV and .MP commands for more information on page management.

state
State information is stored in the available bits (9 - 11) of the page table entry. These are interpreted on the right-hand end of the display. The following values may appear:

┌──────────┬─────┬─────────────────────────┐
│State     │Value│Description              │
├──────────┼─────┼─────────────────────────┤
│pageable  │0    │Storage may be paged-out │
│          │     │to the swap file         │
├──────────┼─────┼─────────────────────────┤
│uvirt     │1    │Physical to virtual      │
│          │     │mapping reservation only.│
├──────────┼─────┼─────────────────────────┤
│resident  │2    │Non-pageable fixed       │
│          │     │storage                  │
├──────────┼─────┼─────────────────────────┤
│uvirt     │3    │Physical to virtual      │
│          │     │mapping reservation only.│
└──────────┴─────┴─────────────────────────┘

Res
Reserved page table entry bits. Should always be zero
Dc
Set to D is the page is dirty, otherwise c (clean).
Au
Set to A if the page has been accessed, otherwise u (unaccessed).
CD
Set to CD is the TLB cache-disable bit is set, else blank.
WT
Set to WT is the TLB cache write-transparent bit is set, else blank.
Us
Set to U if the page is for user storage, otherwise s (supervisor).
rW
Set to r is the page is read-only, otherwise W (writeable).
Pn
Set to P if the page is present, otherwise n (not present).

Note:

The Dump Formatter does not format page directory entries correctly. For page directory entries only the frame field is correct. The remaining fields are taken from the first PTE of the page table associated with the page diretory. This problem has been fixed from fix pack 36 for Warp 3.0 and fix pack 7 for Warp 4.0.

Refer to the following for more information on page and memory management:

• M family of Kernel Debugger and Dump Formatter commands.

  Intel Pentium User's Guide and Intel x86 Programmer's Reference.

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