diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c
new file mode 100644
index 0000000..7604c40
--- /dev/null
+++ b/arch/um/os-Linux/sigio.c
@@ -0,0 +1,324 @@
+/*
+ * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <termios.h>
+#include <pty.h>
+#include <signal.h>
+#include <errno.h>
+#include <string.h>
+#include <sched.h>
+#include <sys/socket.h>
+#include <sys/poll.h>
+#include "init.h"
+#include "user.h"
+#include "kern_util.h"
+#include "user_util.h"
+#include "sigio.h"
+#include "os.h"
+
+/* Protected by sigio_lock(), also used by sigio_cleanup, which is an
+ * exitcall.
+ */
+static int write_sigio_pid = -1;
+
+/* These arrays are initialized before the sigio thread is started, and
+ * the descriptors closed after it is killed.  So, it can't see them change.
+ * On the UML side, they are changed under the sigio_lock.
+ */
+static int write_sigio_fds[2] = { -1, -1 };
+static int sigio_private[2] = { -1, -1 };
+
+struct pollfds {
+	struct pollfd *poll;
+	int size;
+	int used;
+};
+
+/* Protected by sigio_lock().  Used by the sigio thread, but the UML thread
+ * synchronizes with it.
+ */
+struct pollfds current_poll = {
+	.poll  		= NULL,
+	.size 		= 0,
+	.used 		= 0
+};
+
+struct pollfds next_poll = {
+	.poll  		= NULL,
+	.size 		= 0,
+	.used 		= 0
+};
+
+static int write_sigio_thread(void *unused)
+{
+	struct pollfds *fds, tmp;
+	struct pollfd *p;
+	int i, n, respond_fd;
+	char c;
+
+        signal(SIGWINCH, SIG_IGN);
+	fds = &current_poll;
+	while(1){
+		n = poll(fds->poll, fds->used, -1);
+		if(n < 0){
+			if(errno == EINTR) continue;
+			printk("write_sigio_thread : poll returned %d, "
+			       "errno = %d\n", n, errno);
+		}
+		for(i = 0; i < fds->used; i++){
+			p = &fds->poll[i];
+			if(p->revents == 0) continue;
+			if(p->fd == sigio_private[1]){
+				n = os_read_file(sigio_private[1], &c, sizeof(c));
+				if(n != sizeof(c))
+					printk("write_sigio_thread : "
+					       "read failed, err = %d\n", -n);
+				tmp = current_poll;
+				current_poll = next_poll;
+				next_poll = tmp;
+				respond_fd = sigio_private[1];
+			}
+			else {
+				respond_fd = write_sigio_fds[1];
+				fds->used--;
+				memmove(&fds->poll[i], &fds->poll[i + 1],
+					(fds->used - i) * sizeof(*fds->poll));
+			}
+
+			n = os_write_file(respond_fd, &c, sizeof(c));
+			if(n != sizeof(c))
+				printk("write_sigio_thread : write failed, "
+				       "err = %d\n", -n);
+		}
+	}
+
+	return 0;
+}
+
+static int need_poll(int n)
+{
+	if(n <= next_poll.size){
+		next_poll.used = n;
+		return(0);
+	}
+	kfree(next_poll.poll);
+	next_poll.poll = um_kmalloc_atomic(n * sizeof(struct pollfd));
+	if(next_poll.poll == NULL){
+		printk("need_poll : failed to allocate new pollfds\n");
+		next_poll.size = 0;
+		next_poll.used = 0;
+		return(-1);
+	}
+	next_poll.size = n;
+	next_poll.used = n;
+	return(0);
+}
+
+/* Must be called with sigio_lock held, because it's needed by the marked
+ * critical section. */
+static void update_thread(void)
+{
+	unsigned long flags;
+	int n;
+	char c;
+
+	flags = set_signals(0);
+	n = os_write_file(sigio_private[0], &c, sizeof(c));
+	if(n != sizeof(c)){
+		printk("update_thread : write failed, err = %d\n", -n);
+		goto fail;
+	}
+
+	n = os_read_file(sigio_private[0], &c, sizeof(c));
+	if(n != sizeof(c)){
+		printk("update_thread : read failed, err = %d\n", -n);
+		goto fail;
+	}
+
+	set_signals(flags);
+	return;
+ fail:
+	/* Critical section start */
+	if(write_sigio_pid != -1)
+		os_kill_process(write_sigio_pid, 1);
+	write_sigio_pid = -1;
+	close(sigio_private[0]);
+	close(sigio_private[1]);
+	close(write_sigio_fds[0]);
+	close(write_sigio_fds[1]);
+	/* Critical section end */
+	set_signals(flags);
+}
+
+int add_sigio_fd(int fd, int read)
+{
+	int err = 0, i, n, events;
+
+	sigio_lock();
+	for(i = 0; i < current_poll.used; i++){
+		if(current_poll.poll[i].fd == fd)
+			goto out;
+	}
+
+	n = current_poll.used + 1;
+	err = need_poll(n);
+	if(err)
+		goto out;
+
+	for(i = 0; i < current_poll.used; i++)
+		next_poll.poll[i] = current_poll.poll[i];
+
+	if(read) events = POLLIN;
+	else events = POLLOUT;
+
+	next_poll.poll[n - 1] = ((struct pollfd) { .fd  	= fd,
+						   .events 	= events,
+						   .revents 	= 0 });
+	update_thread();
+ out:
+	sigio_unlock();
+	return(err);
+}
+
+int ignore_sigio_fd(int fd)
+{
+	struct pollfd *p;
+	int err = 0, i, n = 0;
+
+	sigio_lock();
+	for(i = 0; i < current_poll.used; i++){
+		if(current_poll.poll[i].fd == fd) break;
+	}
+	if(i == current_poll.used)
+		goto out;
+
+	err = need_poll(current_poll.used - 1);
+	if(err)
+		goto out;
+
+	for(i = 0; i < current_poll.used; i++){
+		p = &current_poll.poll[i];
+		if(p->fd != fd) next_poll.poll[n++] = current_poll.poll[i];
+	}
+	if(n == i){
+		printk("ignore_sigio_fd : fd %d not found\n", fd);
+		err = -1;
+		goto out;
+	}
+
+	update_thread();
+ out:
+	sigio_unlock();
+	return(err);
+}
+
+static struct pollfd *setup_initial_poll(int fd)
+{
+	struct pollfd *p;
+
+	p = um_kmalloc(sizeof(struct pollfd));
+	if (p == NULL) {
+		printk("setup_initial_poll : failed to allocate poll\n");
+		return NULL;
+	}
+	*p = ((struct pollfd) { .fd  	= fd,
+				.events 	= POLLIN,
+				.revents 	= 0 });
+	return p;
+}
+
+void write_sigio_workaround(void)
+{
+	unsigned long stack;
+	struct pollfd *p;
+	int err;
+	int l_write_sigio_fds[2];
+	int l_sigio_private[2];
+	int l_write_sigio_pid;
+
+	/* We call this *tons* of times - and most ones we must just fail. */
+	sigio_lock();
+	l_write_sigio_pid = write_sigio_pid;
+	sigio_unlock();
+
+	if (l_write_sigio_pid != -1)
+		return;
+
+	err = os_pipe(l_write_sigio_fds, 1, 1);
+	if(err < 0){
+		printk("write_sigio_workaround - os_pipe 1 failed, "
+		       "err = %d\n", -err);
+		return;
+	}
+	err = os_pipe(l_sigio_private, 1, 1);
+	if(err < 0){
+		printk("write_sigio_workaround - os_pipe 2 failed, "
+		       "err = %d\n", -err);
+		goto out_close1;
+	}
+
+	p = setup_initial_poll(l_sigio_private[1]);
+	if(!p)
+		goto out_close2;
+
+	sigio_lock();
+
+	/* Did we race? Don't try to optimize this, please, it's not so likely
+	 * to happen, and no more than once at the boot. */
+	if(write_sigio_pid != -1)
+		goto out_unlock;
+
+	write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
+					    CLONE_FILES | CLONE_VM, &stack, 0);
+
+	if (write_sigio_pid < 0)
+		goto out_clear;
+
+	if (write_sigio_irq(l_write_sigio_fds[0]))
+		goto out_kill;
+
+	/* Success, finally. */
+	memcpy(write_sigio_fds, l_write_sigio_fds, sizeof(l_write_sigio_fds));
+	memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
+
+	current_poll = ((struct pollfds) { .poll 	= p,
+					   .used 	= 1,
+					   .size 	= 1 });
+
+	sigio_unlock();
+	return;
+
+ out_kill:
+	l_write_sigio_pid = write_sigio_pid;
+	write_sigio_pid = -1;
+	sigio_unlock();
+	/* Going to call waitpid, avoid holding the lock. */
+	os_kill_process(l_write_sigio_pid, 1);
+	goto out_free;
+
+ out_clear:
+	write_sigio_pid = -1;
+ out_unlock:
+	sigio_unlock();
+ out_free:
+	kfree(p);
+ out_close2:
+	close(l_sigio_private[0]);
+	close(l_sigio_private[1]);
+ out_close1:
+	close(l_write_sigio_fds[0]);
+	close(l_write_sigio_fds[1]);
+	return;
+}
+
+void sigio_cleanup(void)
+{
+	if(write_sigio_pid != -1){
+		os_kill_process(write_sigio_pid, 1);
+		write_sigio_pid = -1;
+	}
+}