Set Segment Limit

Returns

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 set)
8022H	invalid selector
8025H	invalid linear address (changing the limit would cause the descriptor to reference a linear address range outside that allowed for DPMI clients.)

Notes

• 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.