um: Remove legacy network transport infrastructure

All legacy network transports have been removed. Vector transports
provide the same capabilities with significantly higher network
throughput. There is no reason to keep the legacy network transport
infrastructure anymore. Remove it to reduce the maintenance burden.

Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Link: https://patch.msgid.link/20250503051710.3286595-4-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Author: btw616

Documentation/virt/uml/user_mode_linux_howto_v2.rst

@@ -147,18 +147,12 @@ The image hostname will be set to the same as the host on which you
 are creating its image. It is a good idea to change that to avoid
 "Oh, bummer, I rebooted the wrong machine".
 
-UML supports two classes of network devices - the older uml_net ones
-which are scheduled for obsoletion. These are called ethX. It also
-supports the newer vector IO devices which are significantly faster
-and have support for some standard virtual network encapsulations like
-Ethernet over GRE and Ethernet over L2TPv3. These are called vec0.
-
-Depending on which one is in use, ``/etc/network/interfaces`` will
-need entries like::
-
-   # legacy UML network devices
-   auto eth0
-   iface eth0 inet dhcp
+UML supports vector I/O high performance network devices which have
+support for some standard virtual network encapsulations like
+Ethernet over GRE and Ethernet over L2TPv3. These are called vecX.
+
+When vector network devices are in use, ``/etc/network/interfaces``
+will need entries like::
 
    # vector UML network devices
    auto vec0

arch/um/configs/i386_defconfig

@@ -52,7 +52,6 @@ CONFIG_PACKET=y
 CONFIG_UNIX=y
 CONFIG_INET=y
 # CONFIG_IPV6 is not set
-CONFIG_UML_NET=y
 CONFIG_EXT4_FS=y
 CONFIG_QUOTA=y
 CONFIG_AUTOFS_FS=m

arch/um/configs/x86_64_defconfig

@@ -51,7 +51,6 @@ CONFIG_PACKET=y
 CONFIG_UNIX=y
 CONFIG_INET=y
 # CONFIG_IPV6 is not set
-CONFIG_UML_NET=y
 CONFIG_EXT4_FS=y
 CONFIG_QUOTA=y
 CONFIG_AUTOFS_FS=m

arch/um/drivers/Kconfig

@@ -124,35 +124,18 @@ endmenu
 menu "UML Network Devices"
 	depends on NET
 
-# UML virtual driver
-config UML_NET
-	bool "Virtual network device"
-	help
-	  While the User-Mode port cannot directly talk to any physical
-	  hardware devices, this choice and the following transport options
-	  provide one or more virtual network devices through which the UML
-	  kernels can talk to each other, the host, and with the host's help,
-	  machines on the outside world.
-
-	  For more information, including explanations of the networking and
-	  sample configurations, see
-	  <http://user-mode-linux.sourceforge.net/old/networking.html>.
-
-	  If you'd like to be able to enable networking in the User-Mode
-	  linux environment, say Y; otherwise say N.  Note that you must
-	  enable at least one of the following transport options to actually
-	  make use of UML networking.
-
 config UML_NET_VECTOR
 	bool "Vector I/O high performance network devices"
 	select MAY_HAVE_RUNTIME_DEPS
 	help
 	  This User-Mode Linux network driver uses multi-message send
 	  and receive functions. The host running the UML guest must have
 	  a linux kernel version above 3.0 and a libc version > 2.13.
-	  This driver provides tap, raw, gre and l2tpv3 network transports
-	  with up to 4 times higher network throughput than the UML network
-	  drivers.
+	  This driver provides tap, raw, gre and l2tpv3 network transports.
+
+	  For more information, including explanations of the networking
+	  and sample configurations, see
+	  <file:Documentation/virt/uml/user_mode_linux_howto_v2.rst>.
 
 endmenu
 

arch/um/drivers/Makefile

@@ -7,7 +7,6 @@
 # in to pcap.o
 
 vector-objs := vector_kern.o vector_user.o vector_transports.o
-net-objs := net_kern.o net_user.o
 mconsole-objs := mconsole_kern.o mconsole_user.o
 hostaudio-objs := hostaudio_kern.o
 ubd-objs := ubd_kern.o ubd_user.o
@@ -29,7 +28,6 @@ obj-$(CONFIG_SSL) += ssl.o
 obj-$(CONFIG_STDERR_CONSOLE) += stderr_console.o
 
 obj-$(CONFIG_UML_NET_VECTOR) += vector.o
-obj-$(CONFIG_UML_NET) += net.o 
 obj-$(CONFIG_MCONSOLE) += mconsole.o
 obj-$(CONFIG_MMAPPER) += mmapper_kern.o 
 obj-$(CONFIG_BLK_DEV_UBD) += ubd.o