[PATCH net-next v4 7/7] docs: netconsole: document local_ip auto-selection

[Gustavo Luiz Duarte <gustavold@gmail.com>]

An unset local_ip is auto-populated from the egress interface at enable
time, but any value the user writes, including 0.0.0.0, is used as-is.
This deviates from the behavior prior to "netconsole: use the address
family instead of the ipv6 flag", which interpreted 0.0.0.0 as unset.

Document this so the distinction between "unset" and "set to 0.0.0.0" is
clear.

Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Gustavo Luiz Duarte <gustavold@gmail.com>
---
 Documentation/networking/netconsole.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/networking/netconsole.rst b/Documentation/networking/netconsole.rst
index 4ab5d7b05cf1..694bca4803d5 100644
--- a/Documentation/networking/netconsole.rst
+++ b/Documentation/networking/netconsole.rst
@@ -141,6 +141,11 @@ The interface exposes these parameters of a netconsole target to userspace:
 	transmit_errors	Number of packet send errors		(read-only)
 	=============== =================================       ============
 
+local_ip is optional: if it is left unset, netconsole derives a source
+address from the egress interface when the target is enabled. Writing any
+value to it, including 0.0.0.0, uses that value verbatim and disables the
+automatic selection.
+
 The "enabled" attribute is also used to control whether the parameters of
 a target can be updated or not -- you can modify the parameters of only
 disabled targets (i.e. if "enabled" is 0).

-- 
2.55.0