v4.19.13 snapshot.
diff --git a/arch/um/drivers/slip_kern.c b/arch/um/drivers/slip_kern.c
new file mode 100644
index 0000000..ed5249f
--- /dev/null
+++ b/arch/um/drivers/slip_kern.c
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL.
+ */
+
+#include <linux/if_arp.h>
+#include <linux/init.h>
+#include <linux/netdevice.h>
+#include <net_kern.h>
+#include "slip.h"
+
+struct slip_init {
+ char *gate_addr;
+};
+
+static void slip_init(struct net_device *dev, void *data)
+{
+ struct uml_net_private *private;
+ struct slip_data *spri;
+ struct slip_init *init = data;
+
+ private = netdev_priv(dev);
+ spri = (struct slip_data *) private->user;
+
+ memset(spri->name, 0, sizeof(spri->name));
+ spri->addr = NULL;
+ spri->gate_addr = init->gate_addr;
+ spri->slave = -1;
+ spri->dev = dev;
+
+ slip_proto_init(&spri->slip);
+
+ dev->hard_header_len = 0;
+ dev->header_ops = NULL;
+ dev->addr_len = 0;
+ dev->type = ARPHRD_SLIP;
+ dev->tx_queue_len = 256;
+ dev->flags = IFF_NOARP;
+ printk("SLIP backend - SLIP IP = %s\n", spri->gate_addr);
+}
+
+static unsigned short slip_protocol(struct sk_buff *skbuff)
+{
+ return htons(ETH_P_IP);
+}
+
+static int slip_read(int fd, struct sk_buff *skb, struct uml_net_private *lp)
+{
+ return slip_user_read(fd, skb_mac_header(skb), skb->dev->mtu,
+ (struct slip_data *) &lp->user);
+}
+
+static int slip_write(int fd, struct sk_buff *skb, struct uml_net_private *lp)
+{
+ return slip_user_write(fd, skb->data, skb->len,
+ (struct slip_data *) &lp->user);
+}
+
+static const struct net_kern_info slip_kern_info = {
+ .init = slip_init,
+ .protocol = slip_protocol,
+ .read = slip_read,
+ .write = slip_write,
+};
+
+static int slip_setup(char *str, char **mac_out, void *data)
+{
+ struct slip_init *init = data;
+
+ *init = ((struct slip_init) { .gate_addr = NULL });
+
+ if (str[0] != '\0')
+ init->gate_addr = str;
+ return 1;
+}
+
+static struct transport slip_transport = {
+ .list = LIST_HEAD_INIT(slip_transport.list),
+ .name = "slip",
+ .setup = slip_setup,
+ .user = &slip_user_info,
+ .kern = &slip_kern_info,
+ .private_size = sizeof(struct slip_data),
+ .setup_size = sizeof(struct slip_init),
+};
+
+static int register_slip(void)
+{
+ register_transport(&slip_transport);
+ return 0;
+}
+
+late_initcall(register_slip);