REAL6410 network connectivity issues with the Development Board and the host

These two days want to try the TFTP download function under the Uboot, so to establish the Development Board and Ubuntu Network connection, encountered some problems in the middle, is recorded, lest forget.

1. At the beginning, whether the PC Ping Development Board or the Development Board ping computer, ping different;

Check the information on the Internet, said that the network cable is also divided and not cross the line, PC directly linked to the Development Board to use a crossover line, while connecting the router to use a non-crossover line, so I found two network cable directly to the router, the results of the Development Board can ping the PC, but the PC Ping the Development Board, this is the second question;

2. The Development Board may ping the PC machine, but the PC machine Ping does not pass the Development Board;

In fact, this is normal, below a section of netizens reply to answer this question:

The host and the virtual functions ping each other because both the host and the virtual machine have the corresponding process (or thread, not clear) waiting for the ping command to arrive, and in the uboot command input state, when the ping command is used, In fact, Uboot first send an ICMP echo request and answer message according to the IP address you enter to the corresponding host, then wait for some time, if the host does not respond after this time, the display ping impassability, the host if sends the reply message in this time to be able to ping pass. You can view the procedure by tracking the call to the program.
     you use a host or virtual machine Ping Development Board, Development Board destroyer in the Main_loop loop (Waiting for user input command), there is no corresponding program or interrupt (Uboot generally do not use interrupts) to detect the host ping command, of course, ping impassability.
    as long as the Development Board can ping the host can use the network cable to download the Linux kernel image or file system.

Simply put is uboot under the single thread, Ubuntu is multi-threaded, so uboot can ping the PC can be through the network port to download the file.

By the way, when the test is entered into Linux, the Development Board and PC read can ping each other, this can also be explained by the above paragraph. And after testing, the PC with wireless connection routing, and Development Board with network cable Connection routes can also ping, that is, do not know how fast the download, tomorrow try.