- Preallocate some memory for ACPI tasks early enough. We cannot use
malloc(9) any more because spin mutex may be held here. The reserved
memory can be tuned via debug.acpi.max_tasks tunable or ACPI_MAX_TASKS
in kernel configuration. The default is 32 tasks.
- Implement a custom taskqueue_fast to wrap the new memory allocation.
This implementation is not the fastest in the world but we are being
conservative here.