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197 lines
7.5 KiB
C
197 lines
7.5 KiB
C
/*-
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* Copyright (c) 1989, 1990 William F. Jolitz
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* William Jolitz.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)segments.h 7.1 (Berkeley) 5/9/91
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*/
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/*
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* 386 Segmentation Data Structures and definitions
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* William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989
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*/
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/*
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* Selectors
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*/
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#define ISPL(s) ((s)&3) /* what is the priority level of a selector */
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#define SEL_KPL 0 /* kernel priority level */
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#define SEL_UPL 3 /* user priority level */
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#define ISLDT(s) ((s)&SEL_LDT) /* is it local or global */
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#define SEL_LDT 4 /* local descriptor table */
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#define IDXSEL(s) (((s)>>3) & 0x1fff) /* index of selector */
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#define LSEL(s,r) (((s)<<3) | SEL_LDT | r) /* a local selector */
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#define GSEL(s,r) (((s)<<3) | r) /* a global selector */
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/*
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* Memory and System segment descriptors
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*/
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struct segment_descriptor {
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unsigned sd_lolimit:16 ; /* segment extent (lsb) */
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unsigned sd_lobase:24 ; /* segment base address (lsb) */
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unsigned sd_type:5 ; /* segment type */
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unsigned sd_dpl:2 ; /* segment descriptor priority level */
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unsigned sd_p:1 ; /* segment descriptor present */
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unsigned sd_hilimit:4 ; /* segment extent (msb) */
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unsigned sd_xx:2 ; /* unused */
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unsigned sd_def32:1 ; /* default 32 vs 16 bit size */
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unsigned sd_gran:1 ; /* limit granularity (byte/page units)*/
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unsigned sd_hibase:8 ; /* segment base address (msb) */
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} ;
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/*
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* Gate descriptors (e.g. indirect descriptors)
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*/
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struct gate_descriptor {
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unsigned gd_looffset:16 ; /* gate offset (lsb) */
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unsigned gd_selector:16 ; /* gate segment selector */
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unsigned gd_stkcpy:5 ; /* number of stack wds to cpy */
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unsigned gd_xx:3 ; /* unused */
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unsigned gd_type:5 ; /* segment type */
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unsigned gd_dpl:2 ; /* segment descriptor priority level */
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unsigned gd_p:1 ; /* segment descriptor present */
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unsigned gd_hioffset:16 ; /* gate offset (msb) */
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} ;
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/*
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* Generic descriptor
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*/
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union descriptor {
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struct segment_descriptor sd;
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struct gate_descriptor gd;
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};
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/* system segments and gate types */
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#define SDT_SYSNULL 0 /* system null */
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#define SDT_SYS286TSS 1 /* system 286 TSS available */
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#define SDT_SYSLDT 2 /* system local descriptor table */
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#define SDT_SYS286BSY 3 /* system 286 TSS busy */
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#define SDT_SYS286CGT 4 /* system 286 call gate */
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#define SDT_SYSTASKGT 5 /* system task gate */
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#define SDT_SYS286IGT 6 /* system 286 interrupt gate */
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#define SDT_SYS286TGT 7 /* system 286 trap gate */
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#define SDT_SYSNULL2 8 /* system null again */
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#define SDT_SYS386TSS 9 /* system 386 TSS available */
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#define SDT_SYSNULL3 10 /* system null again */
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#define SDT_SYS386BSY 11 /* system 386 TSS busy */
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#define SDT_SYS386CGT 12 /* system 386 call gate */
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#define SDT_SYSNULL4 13 /* system null again */
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#define SDT_SYS386IGT 14 /* system 386 interrupt gate */
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#define SDT_SYS386TGT 15 /* system 386 trap gate */
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/* memory segment types */
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#define SDT_MEMRO 16 /* memory read only */
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#define SDT_MEMROA 17 /* memory read only accessed */
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#define SDT_MEMRW 18 /* memory read write */
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#define SDT_MEMRWA 19 /* memory read write accessed */
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#define SDT_MEMROD 20 /* memory read only expand dwn limit */
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#define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */
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#define SDT_MEMRWD 22 /* memory read write expand dwn limit */
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#define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */
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#define SDT_MEME 24 /* memory execute only */
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#define SDT_MEMEA 25 /* memory execute only accessed */
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#define SDT_MEMER 26 /* memory execute read */
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#define SDT_MEMERA 27 /* memory execute read accessed */
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#define SDT_MEMEC 28 /* memory execute only conforming */
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#define SDT_MEMEAC 29 /* memory execute only accessed conforming */
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#define SDT_MEMERC 30 /* memory execute read conforming */
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#define SDT_MEMERAC 31 /* memory execute read accessed conforming */
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/* is memory segment descriptor pointer ? */
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#define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC)
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/* is 286 gate descriptor pointer ? */
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#define IS286GDP(s) (((s->d_type) >= SDT_SYS286CGT \
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&& (s->d_type) < SDT_SYS286TGT))
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/* is 386 gate descriptor pointer ? */
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#define IS386GDP(s) (((s->d_type) >= SDT_SYS386CGT \
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&& (s->d_type) < SDT_SYS386TGT))
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/* is gate descriptor pointer ? */
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#define ISGDP(s) (IS286GDP(s) || IS386GDP(s))
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/* is segment descriptor pointer ? */
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#define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s))
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/* is system segment descriptor pointer ? */
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#define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s))
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/*
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* Software definitions are in this convenient format,
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* which are translated into inconvenient segment descriptors
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* when needed to be used by the 386 hardware
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*/
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struct soft_segment_descriptor {
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unsigned ssd_base ; /* segment base address */
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unsigned ssd_limit ; /* segment extent */
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unsigned ssd_type:5 ; /* segment type */
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unsigned ssd_dpl:2 ; /* segment descriptor priority level */
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unsigned ssd_p:1 ; /* segment descriptor present */
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unsigned ssd_xx:4 ; /* unused */
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unsigned ssd_xx1:2 ; /* unused */
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unsigned ssd_def32:1 ; /* default 32 vs 16 bit size */
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unsigned ssd_gran:1 ; /* limit granularity (byte/page units)*/
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};
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extern ssdtosd() ; /* to decode a ssd */
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extern sdtossd() ; /* to encode a sd */
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/*
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* region descriptors, used to load gdt/idt tables before segments yet exist.
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*/
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struct region_descriptor {
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unsigned rd_limit:16; /* segment extent */
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unsigned rd_base:32; /* base address */
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};
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/*
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* Segment Protection Exception code bits
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*/
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#define SEGEX_EXT 0x01 /* recursive or externally induced */
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#define SEGEX_IDT 0x02 /* interrupt descriptor table */
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#define SEGEX_TI 0x04 /* local descriptor table */
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/* other bits are affected descriptor index */
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#define SEGEX_IDX(s) ((s)>>3)&0x1fff)
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/*
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* Size of IDT table
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*/
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#define NIDT 256
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#define NRSVIDT 32 /* reserved entries for cpu exceptions */
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