Debugging ARM kernels using fast interrupts

Posted Jun 3, 2014 9:44 UTC (Tue) by Shoragan (subscriber, #46596)
Parent article: Debugging ARM kernels using fast interrupts

AFAIK, the BeagleBone (like other TI Cortex-A SoCs) does not support FIQs. They seems to be reserved for the ROM-code.

Debugging ARM kernels using fast interrupts

Posted Jun 3, 2014 16:31 UTC (Tue) by mces (subscriber, #27668) [Link] (2 responses)

Yes, on my Element14's BBB the boot ROM in the TI chip apparently switches the ARM CPU to "non-trusted" mode before jumping into the first bootloader code. Setting the FIQ bit (to disable FIQs) always fails silently.

No FIQ on BeagleBone Black

Posted Jun 4, 2014 9:10 UTC (Wed) by danielthompson (subscriber, #97243) [Link] (1 responses)

Thanks for this information (even if it is rather disappointing).

I picked the BBB after checking the technical reference manual's section on the interrupt controller... sadly I neglected to check out how the boot ROM works.

The real goal here is to find a widely available (and cheap) board that can be used as an example. I will have to take another look around.

No FIQ on BeagleBone Black

Posted Jun 4, 2014 19:42 UTC (Wed) by Shoragan (subscriber, #46596) [Link]

You could use the raspi, but they seem to (ab)use the FIQ for their USB host driver.

Another alternative would be one of the dozens of i.MX6 boards. Freescale doesn't lock you out of secure mode, so you can use FIQs.