diff options
author | wdenk <wdenk> | 2002-11-18 00:14:45 +0000 |
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committer | wdenk <wdenk> | 2002-11-18 00:14:45 +0000 |
commit | 2262cfeef91458b01a1bfe3812ccbbfdf8b82807 (patch) | |
tree | 3657d48c8ce9089fc96682848859d035a1e8f115 /lib_i386/realmode.c | |
parent | 1d0350ed0b1b0f63e3fb5db6b19397b84a2ea1c7 (diff) |
* Patch by Daniel Engström, 13 Nov 2002:
Add support for i386 architecture and AMD SC520 board
* Patch by Pierre Aubert, 12 Nov 2002:
Add support for DOS filesystem and booting from DOS floppy disk
Diffstat (limited to 'lib_i386/realmode.c')
-rw-r--r-- | lib_i386/realmode.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/lib_i386/realmode.c b/lib_i386/realmode.c new file mode 100644 index 0000000000..372147cf24 --- /dev/null +++ b/lib_i386/realmode.c @@ -0,0 +1,69 @@ +/* + * (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> + + +#define REALMODE_BASE ((char*)0x7c0) +#define REALMODE_MAILBOX ((char*)0xe00) + + +extern char realmode_enter; + + +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; + } + + /* 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, i386boot_realmode, i386boot_realmode_size); + + + 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__ volatile ( + "lcall $0x20,%0\n" : : "i" (&realmode_enter) ); + + memcpy(out, REALMODE_MAILBOX, sizeof(struct pt_regs)); + + return out->eax; +} + |