summaryrefslogtreecommitdiffstats
path: root/qemu/roms/u-boot/doc/README.link-local
diff options
context:
space:
mode:
authorYang Zhang <yang.z.zhang@intel.com>2015-08-28 09:58:54 +0800
committerYang Zhang <yang.z.zhang@intel.com>2015-09-01 12:44:00 +0800
commite44e3482bdb4d0ebde2d8b41830ac2cdb07948fb (patch)
tree66b09f592c55df2878107a468a91d21506104d3f /qemu/roms/u-boot/doc/README.link-local
parent9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (diff)
Add qemu 2.4.0
Change-Id: Ic99cbad4b61f8b127b7dc74d04576c0bcbaaf4f5 Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
Diffstat (limited to 'qemu/roms/u-boot/doc/README.link-local')
-rw-r--r--qemu/roms/u-boot/doc/README.link-local75
1 files changed, 75 insertions, 0 deletions
diff --git a/qemu/roms/u-boot/doc/README.link-local b/qemu/roms/u-boot/doc/README.link-local
new file mode 100644
index 000000000..9586eca26
--- /dev/null
+++ b/qemu/roms/u-boot/doc/README.link-local
@@ -0,0 +1,75 @@
+------------------------------------------
+ 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" \