/*
* (C) Copyright 2002
* Daniel Engström, Omicron Ceti AB, daniel@omicron.se
- *
+ *
* See file CREDITS for list of people who contributed to this
* project.
*
#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;
}
-
- /* 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));
+
+ if (realmode_setup()) {
return -1;
}
-
- memcpy(REALMODE_BASE, i386boot_realmode, i386boot_realmode_size);
-
-
+
in->eip = off;
in->xcs = seg;
- if (3>in->esp & 0xffff) {
+ 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 (
+ 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;
+}