G1-266P-85-1.8
| Model | G1-266P-85-1.8 |
| Description | Processor Series Low Power Integrated x86 Solution |
| PDF file | Total 247 pages (File size: 4M) |
| Chip Manufacturer | NSC |
Geode™ GX1 Processor Series
Processor Programming
(Continued)
3.6.5 Exceptions in Real Mode
Many of the exceptions described in Table 3-29 "Interrupt
mode. Exceptions 10, 11, and 14 do not occur in real
mode. Other exceptions have slightly different meanings in
real mode as listed in Table 3-31.
3.6.6 Error Codes
When operating in protected mode, the following exceptions
generate a 16-bit error code:
•
•
•
•
•
•
•
Double Fault
Alignment Check
Invalid TSS
Segment Not Present
Stack Fault
General Protection Fault
Page Fault
Table 3-31. Exception Changes in Real Mode
Vector
Number
8
10
11
12
13
Protected Mode
Function
Double fault.
Invalid TSS.
Segment not
present.
Stack fault.
General protec-
tion fault.
Real Mode
Function
Interrupt table limit overrun.
Does not occur.
Does not occur.
SS segment limit overrun.
CS, DS, ES, FS, GS seg-
ment limit overrun. In pro-
tected mode, an error code
is pushed. In real mode, no
error code is pushed.
Does not occur.
The error code format and bit definitions are shown in Table
error code was generated as the result of a page fault. The
error code is always zero for double faults and alignment
check exceptions.
14
Page fault.
Table 3-32. Error Codes
15
14
13
12
11
10
9
8
7
6
5
4
3
2
S2
1
S1
0
S0
Selector Index
Table 3-33. Error Code Bit Definitions
Fault
Type
Page
Fault
Selector Index
(Bits 15:3)
Reserved.
S2 (Bit 2)
Fault caused by:
0 = Not present page
1 = Page-level protection
violation
Index of faulty IDT
selector.
Index of faulty
selector.
Reserved
S1 (Bit 1)
Fault occurred during:
0 = Read access
1 = Write access
1
S0 (Bit 0)
Fault occurred during:
0 = Supervisor access
1 = User access.
If = 1: exception occurred while
trying to invoke exception or
hardware interrupt handler.
If=1:
exception occurred while trying
to invoke exception or hardware
interrupt handler.
IDT Fault
Segment
Fault
TI bit of faulty selector
0
www.national.com
82
Revision 1.0
