Set Segment Limit
Sets the limit field in the LDT descriptor for the specified
AX = 0008H
BX = selector
CX:DX = 32-bit segment limit
if function successful
Carry flag = clear
if function unsuccessful
Carry flag = set
AX = error code
|8021H||invalid value (CX <> 0 on a 16-bit DPMI host; or
the limit is greater than 1 MB, but the low twelve bits are not
|8025H||invalid linear address (changing the limit would
cause the descriptor to reference a linear address range outside that
allowed for DPMI clients.)|
- The value supplied to the function in CX:DX is the byte length of
the segment-1 (i.e., the value returned by the LSL instruction).
- Segment limits greater than or equal to 1 MB must be
page-aligned. That is, limits greater than 1 MB must
have the low 12 bits set.
- This function has an implicit effect on the "G" (granularity) bit
in an 80386 descriptor's extended access rights/type byte; i.e., it is
the host's responsibility to set the "G" bit correctly.
- Client programs must use the LSL instruction to query the limit
for a descriptor. Note that on 80386 machines, the client must use
the 32-bit form of LSL if the segment size is greater than 64 KB.
- A DPMI 1.0 host will reload any segment registers which contain
the selector specified in register BX. It is suggested that DPMI 0.9
hosts also implement this.
- Refer to the rules for descriptor usage in Appendix D.