From 6427c165275fe11634862149002c7867f25d02f6 Mon Sep 17 00:00:00 2001 From: Anton Ivanov Date: Tue, 4 Jan 2022 10:44:57 +0000 Subject: um: Document dtb command line option Add documentation for the dtb command line option and the ability to load/parse device trees. Signed-off-by: Anton Ivanov Reviewed-by: Vincent Whitchurch Signed-off-by: Richard Weinberger --- Documentation/virt/uml/user_mode_linux_howto_v2.rst | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'Documentation/virt') diff --git a/Documentation/virt/uml/user_mode_linux_howto_v2.rst b/Documentation/virt/uml/user_mode_linux_howto_v2.rst index 2cafd3c3c6cb..81986fe014d4 100644 --- a/Documentation/virt/uml/user_mode_linux_howto_v2.rst +++ b/Documentation/virt/uml/user_mode_linux_howto_v2.rst @@ -1189,6 +1189,26 @@ E.g. ``os_close_file()`` is just a wrapper around ``close()`` which ensures that the userspace function close does not clash with similarly named function(s) in the kernel part. +Using UML as a Test Platform +============================ + +UML is an excellent test platform for device driver development. As +with most things UML, "some user assembly may be required". It is +up to the user to build their emulation environment. UML at present +provides only the kernel infrastructure. + +Part of this infrastructure is the ability to load and parse fdt +device tree blobs as used in Arm or Open Firmware platforms. These +are supplied as an optional extra argument to the kernel command +line:: + + dtb=filename + +The device tree is loaded and parsed at boottime and is accessible by +drivers which query it. At this moment in time this facility is +intended solely for development purposes. UML's own devices do not +query the device tree. + Security Considerations ----------------------- -- cgit v1.2.3 From 4ef5a0b2e1b806203831b0a7a044539f6627116a Mon Sep 17 00:00:00 2001 From: Vincent Whitchurch Date: Thu, 10 Mar 2022 13:42:30 +0100 Subject: docs: UML: Mention telnetd for port channel It is not obvious from the documentation that using the "port" channel for the console requires telnetd to be installed (see port_connection() in arch/um/drivers/port_user.c). Mention this, and the fact that UML will not boot until a client connects. Signed-off-by: Vincent Whitchurch Acked-by: Anton Ivanov Signed-off-by: Richard Weinberger --- Documentation/virt/uml/user_mode_linux_howto_v2.rst | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'Documentation/virt') diff --git a/Documentation/virt/uml/user_mode_linux_howto_v2.rst b/Documentation/virt/uml/user_mode_linux_howto_v2.rst index 81986fe014d4..863f67b72c05 100644 --- a/Documentation/virt/uml/user_mode_linux_howto_v2.rst +++ b/Documentation/virt/uml/user_mode_linux_howto_v2.rst @@ -664,7 +664,11 @@ one is input, the second one output. * The fd channel - use file descriptor numbers for input/output. Example: ``con1=fd:0,fd:1.`` -* The port channel - listen on TCP port number. Example: ``con1=port:4321`` +* The port channel - start a telnet server on TCP port number. Example: + ``con1=port:4321``. The host must have /usr/sbin/in.telnetd (usually part of + a telnetd package) and the port-helper from the UML utilities (see the + information for the xterm channel below). UML will not boot until a client + connects. * The pty and pts channels - use system pty/pts. -- cgit v1.2.3