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EMAC boot question - 4 minutes to skip it?

Frank Van Hooft1
Expert 1120 points

We've set our SYSBOOT configuration to 00111b, which is the boot order:

EMAC1
MMC0
XIP
NAND

We have nothing plugged into the ethernet ports, and we don't have a NOR flash (so nothing for XIP). We do have an SD Card, and a NAND flash.

When we power on the board, it takes 4 minutes to boot to either the SD Card, or to NAND.

Is this normal? Should we expect the EMAC boot portion of the ROM bootloader to take 4 minutes before deciding there's nothing connected and moving to the next boot device?

Thanks.

  • 0
    TI__Guru 63145 points

    Please read Advisory 1.0.25 in the AM335x Silicon Errata.

    Regards,
    Paul

  • 0 in reply to peaves
    Expert 1120 points

    Thanks for the pointer Paul - I hadn't seen the errata doc had been recently updated.

    Do you happen to know if that errata item is going to be fixed in the next silicon revision (2.1 or whatever it's called)? 

    Regards,

    Frank.

  • 0 in reply to Frank Van Hooft1
    TI__Mastermind 27890 points

    Frank,

    This issue remains in r2.1 silicon. There are currently no plans to fix it.

  • 0 in reply to Frank Van Hooft1
    TI__Guru 63145 points

    No.  We created an advisory for this issue because customers like yourself did not expect this delay, but it was implemented for a specific purpose.

    For example, it may take several minutes for the boot server to boot up and reply to the BOOTP packets from an industrial product like an HMI attached to an CNC milling machine after a temporary power outage.

    This delay was added so a system similar to the one described in the example above would be able to reboot.

    Regards,
    Paul

  • 0 in reply to peaves
    Expert 1120 points

    Thanks very much for the quick responses.

  • 0 in reply to peaves
    Expert 2690 points

    Hi Paul,

    I understand why you implemented the system the way you did and when it can be useful.

    Still, there are plenty of use cases when the opposite behaviour, of breaking into the default boot sequence could be highly desirable. I think there could be lots of customers who could benefit from it. It indeed could be implemented by system just trying to boot from the network once and continuing for next boot device if no success achieved in 4 seconds.

    The proposed advisory has a major disadvantage of requiring additional system level feature to indicate the desired behaviour change (like switch). For example such additional solution can't be used in our systems. There is no direct access to the system internals and the only outside connector is the Ethernet.

    May I suggest you consider adding it in future revisions? You could for instance allow the users to choose between the current behaviour (of long Ethernet wait) and the new (short Ethernet boot attempt) by using one of reserved SYSBOOT pins (13:12).

    Best,
    Vasili

  • 0 in reply to Vasili Galka
    TI__Guru 63145 points

    Thanks for your suggestion.  ROM code changes require a silicon revision and no silicon updates are planned for AM335x at this time.

    Regards,
    Paul

  • 0 in reply to peaves
    Expert 2690 points

    Well, just consider it if an update comes in the future :-)