/* * (C) Copyright 2002 * Daniel Engstr�m, 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 char realmode_enter; int realmode_setup(void) { /* 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; }