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/*
* Mach Operating System
* Copyright (c) 1991,1990 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
* Kernel task state segment.
*
* We don't use the i386 task switch mechanism. We need a TSS
* only to hold the kernel stack pointer for the current thread.
*
* XXX multiprocessor??
*/
#include "vm_param.h"
#include "seg.h"
#include "gdt.h"
#include "ktss.h"
void
ktss_init()
{
/* XXX temporary exception stack */
static exception_stack[1024];
/* Initialize the master TSS descriptor. */
fill_gdt_descriptor(KERNEL_TSS,
kvtolin(&ktss), sizeof(ktss)+65536/8+1-1,
ACC_PL_K|ACC_TSS, 0);
/* Initialize the master TSS. */
ktss.ss0 = KERNEL_DS;
ktss.esp0 = (unsigned)(exception_stack+1024);
ktss.io_bit_map_offset = sizeof(ktss);
/* Set the last byte in the I/O bitmap to all 1's. */
((unsigned char*)&ktss)[sizeof(ktss)+65536/8] = 0xff;
/* Load the TSS. */
ltr(KERNEL_TSS);
}
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