On Fri, 2021-06-11 at 12:36 +0100, Richard Purdie via lists.yoctoproject.org wrote:

as a .cfg to the kernel and that still reproduced the crash. However:

CONFIG_DEBUG_KERNEL=y
CONFIG_CGROUP_DEBUG=y
CONFIG_SCHED_DEBUG=y
CONFIG_DEBUG_PREEMPT=y
# CONFIG_RCU_TRACE is not set
# CONFIG_X86_DEBUG_FPU is not set
# CONFIG_CONSOLE_POLL is not set
# CONFIG_DEBUG_INFO is not set
# CONFIG_KGDB is not set
# CONFIG_KGDB_HONOUR_BLOCKLIST is not set
# CONFIG_KGDB_SERIAL_CONSOLE is not set
# CONFIG_KGDB_LOW_LEVEL_TRAP is not set
# CONFIG_KGDB_KDB is not set
# CONFIG_KDB_KEYBOARD is not set
# CONFIG_DEBUG_MISC is not set

Isolated down to CONFIG_SCHED_DEBUG=y being the line which somehow "fixes"
the crash. I can enable all the above apart from that and we can reproduce
it.

Also, I changed gatesgarth to use qemu 5.2.0 copied in from hardknott and that
breaks it. Dropping the 27 CVE patches "fixes" it again. It is possible it
is one of the CVE fixes. Continuing to try and isolate.

Cheers,

Richard