Re: [U-Boot] [PATCH] Adds basic support for ProxyDHCP

On Mon, Aug 05, 2019 at 06:23:42AM -0400, lylejfranklin@gmail.com wrote:

From: Lyle Franklin lylejfranklin@gmail.com

• 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

Sorry for the delay, applied to u-boot/next, thanks!