cpu/core: Fix "help" of CPU core device types Thomas Huth recently reported an annoying crash: $ ./qemu-system-ppc64 -device power8_v2.0-spapr-cpu-core,help /home/thuth/devel/qemu/include/hw/boards.h:24: MACHINE: Object 0x5635bd53af10 is not an instance of type machine Aborted (core dumped) This is caused by an early use of qdev_get_machine(), before the machine creation, which triggers a side-effect of creating a dummy "container" object instead of the machine. This is needed by user mode emulation, which doesn't really care about the type of the parent of the CPU model. This is toxic for system mode though because the system mode specific code usually assume MACHINE(qdev_get_machine()). This series brings separate implementations between user and system mode. The breakage with "cpu-code,help" is fixed by using current_machine.