Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

R

16.1.3.PGTBL_ER—Page Table Error Register

Address Offset:

02024h (identical functionality in Device 0 at EC–EFh)

Default Value:

0000 0000h

Access:

Read Only

Size:

32 bits

This register stores information pertaining to page table error interrupts. Invalid physical address implies regions in main memory that have restricted accessibility such as PAM/SMM space etc.

The Display engine speculatively fetches data, and may cross 16 GTT mapped pages that are not intended for use. To prevent errors from occurring and hanging the display engine, the 16 GTT pages adjacent to the contiguous display region must be left unused but marked valid and mapped.

Once a page table error has been detected, the GMCH hardware will operate in an error state but continues to complete host cycles to memory in order to facilitate system debug (as opposed to hanging the system.) In the page table error detected state, further read will complete normally, whereas write will complete with all byte enables masked.

The page table error condition within the GMCH can be recovered by software writing a ‘1’ to bit 15 of the Interrupt Identity Register (IIR.) Note that this action is in addition to software clearing the page table error identification bit in the Error Identity Register (EIR[4].)

 

31

 

12

 

11

6

5

3

2

0

 

 

 

 

Physical Address 31:12

 

Reserved

 

Error ID

 

Error Type

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bit

 

Description

 

 

 

 

 

 

 

 

 

 

 

31:12

Physical Address. This field provides the page table access address for a page table Error Type 4,

 

 

 

(i.e. bits 2:0 = “100”) indicating a translated address that points to PAM, SMM, and other restricted

 

 

 

 

spaces in main memory. This field is normally undefined and only registers a valid entry upon an

 

 

 

occurrence of a page table error type 4. Occurrence of a page table error type 4 is recorded in

 

 

 

 

MMIO register 20B8h, Error Status Register, bit 4.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

11:6

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

5:3

Error Identification: Identifies the TLB that caused the error. After an error Render, Mapping and

 

 

 

 

Blitter engines will stop execution. However, overlay, display and host operations will not stop. Each

 

 

 

Source records the first error and ignores subsequent errors. See the Page Table Error Mask

 

 

 

 

Register for more debug help.

 

 

 

 

 

 

 

 

 

000

= Buffer (BF) Unit

 

 

 

 

 

 

 

 

 

001

= Overlay

 

 

 

 

 

 

 

 

 

010

= Display

 

 

 

 

 

 

 

 

 

011

= Host

 

 

 

 

 

 

 

 

 

100

= Render

 

 

 

 

 

 

 

 

 

101

= Blitter

 

 

 

 

 

 

 

 

 

110

= Mapping

 

 

 

 

 

 

 

 

 

111

= Command Stream

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

304

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Intel 815 manual PGTBLER-Page Table Error Register