Adds basic support for ProxyDHCP
- ProxyDHCP allows a second DHCP server to exist alongside your main
DHCP server and supply additional BOOTP related options
- When u-boot sends out a DHCP request, the real DHCP server will
respond with a normal response containing the new client IP address
while simultaneously the ProxyDHCP server will respond with a blank
client IP address and a `bootfile` option
- This patch adds CONFIG_SERVERIP_FROM_PROXYDHCP (default false) to
enable this behavior and CONFIG_SERVERIP_FROM_PROXYDHCP_DELAY_MS
(default 100) which tells u-boot to wait additional time after
receiving the main DHCP response to give the ProxyDHCP response time
to arrive
- The PXE spec for ProxyDHCP is more complicated than the solution
added here as diagramed on page 16:
http://www.pix.net/software/pxeboot/archive/pxespec.pdf:
```
DHCP Discover will be retried four times. The four timeouts are 4, 8, 16
and 32 seconds respectively. If a DHCPOFFER is received without an Option
timeouts in an attempt to receive a PXE response.
```
- Adding a simple delay worked for my purposes but let me know if a
more robust solution is required
Signed-off-by: Lyle Franklin <lylejfranklin@gmail.com>
diff --git a/net/Kconfig b/net/Kconfig
index 1b3e420..c4b4dae 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -74,4 +74,18 @@
before an ack response is required.
The default TFTP implementation implies a window size of 1.
+config SERVERIP_FROM_PROXYDHCP
+ bool "Get serverip value from Proxy DHCP response"
+ help
+ Allows bootfile config to be fetched from Proxy DHCP server
+ while IP is obtained from main DHCP server.
+
+config SERVERIP_FROM_PROXYDHCP_DELAY_MS
+ int "# of additional milliseconds to wait for ProxyDHCP response"
+ default 100
+ help
+ Amount of additional time to wait for ProxyDHCP response after
+ receiving response from main DHCP server. Has no effect if
+ SERVERIP_FROM_PROXYDHCP is false.
+
endif # if NET