Marek VasutandHeinrich Schuchardt
dc3765ede5
The "env" command is the recommended environment management command, its "set" subcommand is the equivalent replacement for legacy "setenv" command. Update the documentation to use the contemporary "env set" command instead of legacy "setenv" command. Note that the "setenv" command is unlikely to be removed from U-Boot in the near future due to it being integral part of the command line ABI. Implemented using: $ sed -i 's@\<setenv\>@env set@g' $(git grep -li '\<setenv\>' doc/) README Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
76 lines
2.3 KiB
Plaintext
76 lines
2.3 KiB
Plaintext
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Link-local IP address auto-configuration
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Negotiate with other link-local clients on the local network
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for an address that doesn't require explicit configuration.
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This is especially useful if a DHCP server cannot be guaranteed
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to exist in all environments that the device must operate.
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This is an implementation of RFC3927.
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----------
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Commands
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----------
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When CONFIG_CMD_LINK_LOCAL is defined in the board config file,
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the "linklocal" command is available. This running this will
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take approximately 5 seconds while the address is negotiated.
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------------------------
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Environment interation
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------------------------
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The "llipaddr" variable is set with the most recently
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negotiated address and is preferred in future negotiations.
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The "ipaddr", "netmask", and "gatewayip" variables are set
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after successful negotiation to enable network access.
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-------------
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Limitations
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-------------
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RFC3927 requires that addresses are continuously checked to
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avoid conflicts, however this can only happen when the net_loop
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is getting called. It is possible for a conflict to go undetected
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until a command that accesses the network is executed.
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Using NetConsole is one way to ensure that net_loop is always
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processing packets and monitoring for conflicts.
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This is also not a concern if the feature is use to connect
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directly to another machine that may not be running a DHCP server.
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----------------
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Example script
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----------------
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This script allows use of DHCP and/or Link-local controlled
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by env variables. It depends on CONFIG_CMD_LINK_LOCAL, CONFIG_CMD_DHCP,
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and CONFIG_BOOTP_MAY_FAIL.
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If both fail or are disabled, static settings are used.
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#define CFG_EXTRA_ENV_SETTINGS \
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"ipconfigcmd=if test \\\"$dhcpenabled\\\" -ne 0;" \
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"then " \
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"dhcpfail=0;dhcp || dhcpfail=1;" \
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"else " \
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"dhcpfail=-1;" \
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"fi;" \
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"if test \\\"$linklocalenabled\\\" -ne 0 -a " \
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"\\\"$dhcpfail\\\" -ne 0;" \
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"then " \
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"linklocal;" \
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"llfail=0;" \
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"else " \
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"llfail=-1;" \
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"fi;" \
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"if test \\\"$llfail\\\" -ne 0 -a " \
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"\\\"$dhcpfail\\\" -ne 0; " \
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"then " \
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"env set ipaddr $sipaddr; " \
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"env set netmask $snetmask; " \
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"env set gatewayip $sgatewayip; " \
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"fi;\0" \
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