xref: /OK3568_Linux_fs/u-boot/doc/README.SNTP (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593SmuzhiyunTo use SNTP support, add define CONFIG_CMD_SNTP to the
2*4882a593Smuzhiyunconfiguration file of the board.
3*4882a593Smuzhiyun
4*4882a593SmuzhiyunThe "sntp" command gets network time from NTP time server and
5*4882a593Smuzhiyunsyncronize RTC of the board. This command needs the command line
6*4882a593Smuzhiyunparameter of server's IP address or environment variable
7*4882a593Smuzhiyun"ntpserverip". The network time is sent as UTC. So if you want to
8*4882a593Smuzhiyunset local time to RTC, set the offset in second from UTC to the
9*4882a593Smuzhiyunenvironment variable "time offset".
10*4882a593Smuzhiyun
11*4882a593SmuzhiyunIf the DHCP server provides time server's IP or time offset, you
12*4882a593Smuzhiyundon't need to set the above environment variables yourself.
13*4882a593Smuzhiyun
14*4882a593SmuzhiyunCurrent limitations of SNTP support:
15*4882a593Smuzhiyun1. The roundtrip time is ignored.
16*4882a593Smuzhiyun2. Only the 1st NTP server IP, in the option ntp-servers of DHCP, will
17*4882a593Smuzhiyun   be used.
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