Intel 80286 - Page 223

THE 80286 INSTRUCTION SET
Set CPL to the RPL of the CS selector in the newTSS
If new stack selector is null #TS(SS)
SS selector must be within its descriptor table limits else #TS(SS)
SS selector RPL must be equal to CPL else #TS(SS)
OPL
of SS descriptor must equal CPL else #TS(SS)
SS descriptor AR byte must indicate writable data segment else #TS(SS)
SS descriptor AR byte must indicate PRESENT else #SS(SS)
Load
SS cache with new stack segment and set valid bit
New
CS selector must not be null else #TS(CS)
CS selector must be within its descriptor table limits else #TS(CS)
CS descriptor AR byte must indicate code segment else #TS(CS)
If non-conforming then OPL must equal CPL else #TS(CS)
If conforming then
OPL must be :::; CPL else #TS(CS)
CS descriptor AR byte must indicate PRESENT else #NP(CS)
Load
CS cache with new code segment descriptor and set valid bit
For
OS and ES:
If new selector is not null then perform following checks:
Index must be within its descriptor table limits else #TS(segment selector)
AR byte must indicate data or readable code else #TS(segment selector)
If data or non-conforming code then:
OPL must be 2': CPL else #TS(segment selector)
OPL must be 2': RPL else #TS(segment selector)
AR byte must indicate PRESENT else #NP(segment selector)
Load cache with new segment descriptor and set valid bit
8-13
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