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/*
* (C) Copyright 2002
* Daniel Engström, Omicron Ceti AB, daniel@omicron.se
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
#include <asm/io.h>
#include <asm/ptrace.h>
#include <asm/realmode.h>
#define REALMODE_BASE ((char*)0x7c0)
#define REALMODE_MAILBOX ((char*)0xe00)
extern ulong _i386boot_realmode;
extern ulong _i386boot_realmode_size;
extern char realmode_enter;
int realmode_setup(void)
{
ulong i386boot_realmode = (ulong)&_i386boot_realmode;
ulong i386boot_realmode_size = (ulong)&_i386boot_realmode_size;
/* copy the realmode switch code */
if (i386boot_realmode_size > (REALMODE_MAILBOX-REALMODE_BASE)) {
printf("realmode switch too large (%ld bytes, max is %d)\n",
i386boot_realmode_size, (REALMODE_MAILBOX-REALMODE_BASE));
return -1;
}
memcpy(REALMODE_BASE, (void*)i386boot_realmode, i386boot_realmode_size);
asm("wbinvd\n");
return 0;
}
int enter_realmode(u16 seg, u16 off, struct pt_regs *in, struct pt_regs *out)
{
/* setup out thin bios emulation */
if (bios_setup()) {
return -1;
}
if (realmode_setup()) {
return -1;
}
in->eip = off;
in->xcs = seg;
if (3>(in->esp & 0xffff)) {
printf("Warning: entering realmode with sp < 4 will fail\n");
}
memcpy(REALMODE_MAILBOX, in, sizeof(struct pt_regs));
asm("wbinvd\n");
__asm__ volatile (
"lcall $0x20,%0\n" : : "i" (&realmode_enter) );
asm("wbinvd\n");
memcpy(out, REALMODE_MAILBOX, sizeof(struct pt_regs));
return out->eax;
}
/* This code is supposed to access a realmode interrupt
* it does currently not work for me */
int enter_realmode_int(u8 lvl, struct pt_regs *in, struct pt_regs *out)
{
/* place two instructions at 0x700 */
writeb(0xcd, 0x700); /* int $lvl */
writeb(lvl, 0x701);
writeb(0xcb, 0x702); /* lret */
asm("wbinvd\n");
enter_realmode(0x00, 0x700, in, out);
return out->eflags&1;
}
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