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Enabling VFP on XEVMK2EX

michael han
Prodigy 30 points

I'm using the XEVMK2EX board and i'm trying to enable VFP.  It seems that I can step through my code on the debugger and use the "SMC 0" command from supervisor mode before enabling VFP.  This will allow me to set the NSCAR and CPSR registers then enable VFP.  However,  if I run the code without stepping through it I get an undefined instruction when attempting to access the NSCAR register to enable VFP. 

I'm not sure what the difference between stepping through the code and running it is but it seems this is causing an issue.  Am I missing a step so I'm able to turn on VFP?

Thanks,

Mike

  • 0
    TI__Guru* 81335 points

    Welcome to the TI E2E forum. I hope you will find many good answers here and in the TI.com documents and in the TI Wiki Pages (for processor issues). Be sure to search those for helpful information and to browse for the questions others may have asked on similar topics (e2e.ti.com). Please read all the links below my signature.

    We will get back to you on the above query shortly. Thank you for your patience.

  • 0
    TI__Guru* 81335 points

    I'm not sure what the difference between stepping through the code and running it is but it seems this is causing an issue.  Am I missing a step so I'm able to turn on VFP?

    You can use boot monitor for this purpose. Try enabling the VFP functions through boot monitor. Please refer below wiki for more information like building and running etc.,

    Thank you

  • 0 in reply to Raja
    Prodigy 30 points

    Thanks Raja,  I'll look into this a bit more.  Do you know if it's possible to do this without linux?  I'm creating a custom RTOS on the board. 

  • 0 in reply to michael han
    TI__Guru* 81335 points

    Hi,

    Do you know if it's possible to do this without linux?  

    The boot monitor pointed above is without the Linux. You can run boot monitor from u-boot.

    (OR)

    Have you looked at the keystone 2 bootloader examples from below link? You can implement VFP enable/disable on top of the bootloader.

    Thank you.

  • 0 in reply to Raja
    Prodigy 30 points

    Thanks Raja,

    I was actually able to figure out the issue.  The use of SMC involves the passing of a the function address to be executed under monitor mode in the r0 register.  Once I figured this out the code was able to be executed without causing an undefined instruction exception.

    -Mike

  • 0 in reply to michael han
    TI__Guru* 81335 points
    We are glad that you were able to solve the issue. Thank you so much for the update.