CONFIG_PREEMPT_VOLUNTARY in bcm2711 32-bit, but CONFIG_PREEMPT for 64-bit

[HinTak]

I am surprised to notice that the PREEMPT option for 32-bit bcm2711 (pi4) build vs 64-bit build is different, one is VOLUNTARY the other is plain PREEMPT (ie full). I assumed that the latter is the variant since raspberry pi can run in 64-bit mode only in the last couple of years with pi3/pi4, until I Google'd and found #1216 .

Anyway, I am wondering if they should differ as little as possible. There are a dozen or so differences in the two defconfig, but this is obviously major.

FWIW, I am looking at the issue because of a sh*tty out-of-tree driver issue which seems to be much more serious with 64-bit kernel, with a kernel panic about "scheduling while atomic"...

[HinTak]

I have read up about this - interestingly, ubuntu had opted for CONFIG_PREEMPT in both their 32-bit and 64-bit build for the opposite reason - to force preemption on unresponsive drivers. Sadly the issue I am looking at, want exactly to be unresponsive - it wants to block until the hardware responds one way or another, and causes kernel panics when run under full preemption...