. . , . , . (. 6.20).
. 6.20. -
( ) . . , , , . , , . , , .
. , . , 1- , : shared () private (). , , ( ).
, .. , . , .
, . 6.21.
, Pentium. Windows 2000 16 . 4 ( 2 2 ). Windows 2000 : LDT (Local Descriptor Table) GDT (Global Descriptor Table). LDT, , . LDT , , , , ..; GDT , .
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. 6.21.
GDTR LDTR GDT LDT. LDTR LDT GTD, LDT .
, . , . (. 6.22). GDT LDT ( 213 = 8 ). , 8 8 , 16 . , 4 ? ( ), 64 .
. 6.22. - Windows
, . Pentium 4 , 0 , 3 . (. 6.23).
. 6.23. Windows
, :
- DPL (Descriptor Privilege Level) DPL ;
- RPL (Requested Privilege Level) , RPL ;
- CPL (Current Privilege Level) , RPL ;
- EPL (Effective Privilege Level) .
. DPL RPL . , . , 2- (PSW). DPL CPL, PSW.
EPL DPL . , :
EPL <= DPL,
EPL = max {CPL, RPL}.
RPL RPL -, .