mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-16 01:38:22 +00:00
76 lines
2.3 KiB
Text
76 lines
2.3 KiB
Text
|
------------------------------------------
|
||
|
|
Link-local IP address auto-configuration
|
||
|
|
------------------------------------------
|
||
|
|
|
||
|
|
Negotiate with other link-local clients on the local network
|
||
|
|
for an address that doesn't require explicit configuration.
|
||
|
|
This is especially useful if a DHCP server cannot be guaranteed
|
||
|
|
to exist in all environments that the device must operate.
|
||
|
|
|
||
|
|
This is an implementation of RFC3927.
|
||
|
|
|
||
|
|
----------
|
||
|
|
Commands
|
||
|
|
----------
|
||
|
|
|
||
|
|
When CONFIG_CMD_LINK_LOCAL is defined in the board config file,
|
||
|
|
the "linklocal" command is available. This running this will
|
||
|
|
take approximately 5 seconds while the address is negotiated.
|
||
|
|
|
||
|
|
------------------------
|
||
|
|
Environment interation
|
||
|
|
------------------------
|
||
|
|
|
||
|
|
The "llipaddr" variable is set with the most recently
|
||
|
|
negotiated address and is preferred in future negotiations.
|
||
|
|
|
||
|
|
The "ipaddr", "netmask", and "gatewayip" variables are set
|
||
|
|
after successful negotiation to enable network access.
|
||
|
|
|
||
|
|
-------------
|
||
|
|
Limitations
|
||
|
|
-------------
|
||
|
|
|
||
|
|
RFC3927 requires that addresses are continuously checked to
|
||
|
|
avoid conflicts, however this can only happen when the NetLoop
|
||
|
|
is getting called. It is possible for a conflict to go undetected
|
||
|
|
until a command that accesses the network is executed.
|
||
|
|
|
||
|
|
Using NetConsole is one way to ensure that NetLoop is always
|
||
|
|
processing packets and monitoring for conflicts.
|
||
|
|
|
||
|
|
This is also not a concern if the feature is use to connect
|
||
|
|
directly to another machine that may not be running a DHCP server.
|
||
|
|
|
||
|
|
----------------
|
||
|
|
Example script
|
||
|
|
----------------
|
||
|
|
|
||
|
|
This script allows use of DHCP and/or Link-local controlled
|
||
|
|
by env variables. It depends on CONFIG_CMD_LINK_LOCAL, CONFIG_CMD_DHCP,
|
||
|
|
and CONFIG_BOOTP_MAY_FAIL.
|
||
|
|
If both fail or are disabled, static settings are used.
|
||
|
|
|
||
|
|
#define CONFIG_EXTRA_ENV_SETTINGS \
|
||
|
|
"ipconfigcmd=if test \\\"$dhcpenabled\\\" -ne 0;" \
|
||
|
|
"then " \
|
||
|
|
"dhcpfail=0;dhcp || dhcpfail=1;" \
|
||
|
|
"else " \
|
||
|
|
"dhcpfail=-1;" \
|
||
|
|
"fi;" \
|
||
|
|
"if test \\\"$linklocalenabled\\\" -ne 0 -a " \
|
||
|
|
"\\\"$dhcpfail\\\" -ne 0;" \
|
||
|
|
"then " \
|
||
|
|
"linklocal;" \
|
||
|
|
"llfail=0;" \
|
||
|
|
"else " \
|
||
|
|
"llfail=-1;" \
|
||
|
|
"fi;" \
|
||
|
|
"if test \\\"$llfail\\\" -ne 0 -a " \
|
||
|
|
"\\\"$dhcpfail\\\" -ne 0; " \
|
||
|
|
"then " \
|
||
|
|
"setenv ipaddr $sipaddr; " \
|
||
|
|
"setenv netmask $snetmask; " \
|
||
|
|
"setenv gatewayip $sgatewayip; " \
|
||
|
|
"fi;\0" \
|