diff --git a/arch/um/sys-i386/ldt.c b/arch/um/sys-i386/ldt.c
new file mode 100644
index 0000000..31bcb2f
--- /dev/null
+++ b/arch/um/sys-i386/ldt.c
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include "linux/config.h"
+#include "linux/slab.h"
+#include "asm/uaccess.h"
+#include "asm/ptrace.h"
+#include "choose-mode.h"
+#include "kern.h"
+
+#ifdef CONFIG_MODE_TT
+extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
+
+/* XXX this needs copy_to_user and copy_from_user */
+
+int sys_modify_ldt_tt(int func, void __user *ptr, unsigned long bytecount)
+{
+	if (!access_ok(VERIFY_READ, ptr, bytecount))
+		return -EFAULT;
+
+	return modify_ldt(func, ptr, bytecount);
+}
+#endif
+
+#ifdef CONFIG_MODE_SKAS
+extern int userspace_pid;
+
+#include "skas_ptrace.h"
+
+int sys_modify_ldt_skas(int func, void __user *ptr, unsigned long bytecount)
+{
+	struct ptrace_ldt ldt;
+	void *buf;
+	int res, n;
+
+	buf = kmalloc(bytecount, GFP_KERNEL);
+	if(buf == NULL)
+		return(-ENOMEM);
+
+	res = 0;
+
+	switch(func){
+	case 1:
+	case 0x11:
+		res = copy_from_user(buf, ptr, bytecount);
+		break;
+	}
+
+	if(res != 0){
+		res = -EFAULT;
+		goto out;
+	}
+
+	ldt = ((struct ptrace_ldt) { .func	= func,
+				     .ptr	= buf,
+				     .bytecount = bytecount });
+	res = ptrace(PTRACE_LDT, userspace_pid, 0, (unsigned long) &ldt);
+	if(res < 0)
+		goto out;
+
+	switch(func){
+	case 0:
+	case 2:
+		n = res;
+		res = copy_to_user(ptr, buf, n);
+		if(res != 0)
+			res = -EFAULT;
+		else 
+			res = n;
+		break;
+	}
+
+ out:
+	kfree(buf);
+	return(res);
+}
+#endif
+
+int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
+{
+	return(CHOOSE_MODE_PROC(sys_modify_ldt_tt, sys_modify_ldt_skas, func, 
+				ptr, bytecount));
+}
+
+
+
+/*
+ * Overrides for Emacs so that we follow Linus's tabbing style.
+ * Emacs will notice this stuff at the end of the file and automatically
+ * adjust the settings for this buffer only.  This must remain at the end
+ * of the file.
+ * ---------------------------------------------------------------------------
+ * Local variables:
+ * c-file-style: "linux"
+ * End:
+ */