projects / J-u-boot.git / blame
| Commit | Line | Data |
|---|---|---|
| 1a32bf41 RG |
1 | Domain Name System |
| 2 | ------------------------------------------- | |
| 3 | ||
| 4 | The Domain Name System (DNS) is a hierarchical naming system for computers, | |
| 5 | services, or any resource participating in the Internet. It associates various | |
| 6 | information with domain names assigned to each of the participants. Most | |
| 7 | importantly, it translates domain names meaningful to humans into the numerical | |
| 8 | (binary) identifiers associated with networking equipment for the purpose of | |
| 9 | locating and addressing these devices world-wide. An often used analogy to | |
| 10 | explain the Domain Name System is that it serves as the "phone book" for the | |
| 11 | Internet by translating human-friendly computer hostnames into IP addresses. | |
| 12 | For example, www.example.com translates to 208.77.188.166. | |
| 13 | ||
| 14 | For more information on DNS - http://en.wikipedia.org/wiki/Domain_Name_System | |
| 15 | ||
| 1a32bf41 RG |
16 | U-Boot and DNS |
| 17 | ------------------------------------------ | |
| 18 | ||
| 19 | CONFIG_CMD_DNS - controls if the 'dns' command is compiled in. If it is, it | |
| 28958b8b WD |
20 | will send name lookups to the dns server (env var 'dnsip') |
| 21 | Turning this option on will about abou 1k to U-Boot's size. | |
| 1a32bf41 | 22 | |
| 28958b8b | 23 | Example: |
| 1a32bf41 RG |
24 | |
| 25 | bfin> print dnsip | |
| 26 | dnsip=192.168.0.1 | |
| 27 | ||
| 28 | bfin> dns www.google.com | |
| 29 | 66.102.1.104 | |
| 30 | ||
| 28958b8b WD |
31 | By default, dns does nothing except print the IP number on |
| 32 | the default console - which by itself, would be pretty | |
| 33 | useless. Adding a third argument to the dns command will | |
| 34 | use that as the environment variable to be set. | |
| 1a32bf41 | 35 | |
| 28958b8b | 36 | Example: |
| 1a32bf41 RG |
37 | |
| 38 | bfin> print googleip | |
| 39 | ## Error: "googleip" not defined | |
| 40 | bfin> dns www.google.com googleip | |
| 41 | 64.233.161.104 | |
| 42 | bfin> print googleip | |
| 43 | googleip=64.233.161.104 | |
| 44 | bfin> ping ${googleip} | |
| 45 | Using Blackfin EMAC device | |
| 46 | host 64.233.161.104 is alive | |
| 47 | ||
| 28958b8b WD |
48 | In this way, you can lookup, and set many more meaningful |
| 49 | things. | |
| 1a32bf41 RG |
50 | |
| 51 | bfin> sntp | |
| 52 | ntpserverip not set | |
| 53 | bfin> dns pool.ntp.org ntpserverip | |
| 54 | 72.18.205.156 | |
| 55 | bfin> sntp | |
| 28958b8b | 56 | Date: 2009-07-18 Time: 4:06:57 |
| 1a32bf41 | 57 | |
| 28958b8b WD |
58 | For some helpful things that can be related to DNS in U-Boot, |
| 59 | look at the top level README for these config options: | |
| 60 | CONFIG_CMD_DHCP | |
| 61 | CONFIG_BOOTP_DNS | |
| 62 | CONFIG_BOOTP_DNS2 |