From: Mark Salter on
gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1408#note_8023...
Back in the RHELSA-7 days, we decided to turn off CONFIG_DEVMEM because
certain userspace tools which were not sufficiently Arm-aware would crash the
kernel. Someone (Applied Micro or Cavium) complained that there was debug
value in having it enabled so we enabled it in -debug kernels. With RHEL-8, we
missed the addition of STRICT_DEVMEM and it defaulted to =y even though DEVMEM
was turned off so it didn't matter. Now we have DEVMEM enabled on RHEL-9 non-
debug kernel. If we're going to leave it enabled, we want STRICT_DEVMEM=y so
it's not so easy to crash the kernel. But turning DEVMEM on only for the
-debug kernel makes the most sense to me.