RPi4 Status and xorg behavior (FreeBSD debug kernel panics for USB storage devices)

[Mark Millard]

There is a known FreeBSD error exposed by recent debug
kernels that panic with backtraces like the following
when USB storage is present or plugged in, not just
on aarch64 or armv7/6 but in general:

panic: malloc(M_WAITOK) with sleeping prohibited
cpuid = 0
time = 1615452946
KDB: stack backtrace:
db_trace_self() at db_trace_self
db_trace_self_wrapper() at db_trace_self_wrapper+0x30
vpanic() at vpanic+0x184
panic() at panic+0x44
malloc_dbg() at malloc_dbg+0xf8
malloc() at malloc+0x30
disk_alloc() at disk_alloc+0x1c
daregister() at daregister+0x3b8
cam_periph_alloc() at cam_periph_alloc+0x528
daasync() at daasync+0x260
xpt_async_process_dev() at xpt_async_process_dev+0x194
xpt_async_process() at xpt_async_process+0x3a0
xpt_done_process() at xpt_done_process+0x314
xpt_done_td() at xpt_done_td+0xd8
fork_exit() at fork_exit+0x74
fork_trampoline() at fork_trampoline+0x14

It turns out that the snapshot:

FreeBSD-14.0-CURRENT-arm64-aarch64-RPI-20210311-15565e0a217-257277.img.xz

Is an example of having this problem. So are the
other "20210311" snapshots with debug kernels.

Recent https://artifact.ci.freebsd.org/snapshot/
materials will also have the problem (debug kernels).

The http://ftp3.freebsd.org/pub/FreeBSD/releases/
material do not have debug kernels and so will not
panic and should work as long as various memory
allocations do not fail.

https://reviews.freebsd.org/D29210/ is for a patch in
review for the issue. Various folks have used it to
get debug kernels going for their activities.

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)