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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"
/* A kernel TSS with a complete I/O bitmap. */
struct task_tss ktss __section(".data.shared");
void
ktss_init(void)
{
/* XXX temporary exception stack */
static int exception_stack[1024] __section(".data.shared");
#ifdef MACH_RING1
/* Xen won't allow us to do any I/O by default anyway, just register
* exception stack */
if (hyp_stack_switch(KERNEL_DS, (unsigned long)(exception_stack+1024)))
panic("couldn't register exception stack\n");
#else /* MACH_RING1 */
/* Initialize the master TSS descriptor. */
fill_gdt_descriptor(KERNEL_TSS,
kvtolin(&ktss), sizeof(struct task_tss) - 1,
ACC_PL_K|ACC_TSS, 0);
/* Initialize the master TSS. */
ktss.tss.ss0 = KERNEL_DS;
ktss.tss.esp0 = (unsigned long)(exception_stack+1024);
ktss.tss.io_bit_map_offset = IOPB_INVAL;
/* Set the last byte in the I/O bitmap to all 1's. */
ktss.barrier = 0xff;
/* Load the TSS. */
ltr(KERNEL_TSS);
#endif /* MACH_RING1 */
}
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