Re: [PATCH v2] hw/misc/vmfwupdate: Introduce hypervisor fw-cfg interface support

[Ani Sinha]

> > Either add the I386 dependency or don't use PC_MACHINE, because on
> > non-x86 targets PC_MACHINE(qdev_get_machine()) will crash.
>
> Ah this is where we have a disconnect. I assumed that
> > pcms = PC_MACHINE(m_obj)
>
> would return NULL on non-x86.
>
> Seems a better way to do this (as is done in vga.c) is to use
> object_dynamic_cast()
> How about
>
> diff --git a/hw/misc/vmfwupdate.c b/hw/misc/vmfwupdate.c
> index 0e90bd10e1..19d042b929 100644
> --- a/hw/misc/vmfwupdate.c
> +++ b/hw/misc/vmfwupdate.c
> @@ -32,9 +32,11 @@ static inline VMFwUpdateState *vmfwupdate_find(void)
>  static uint64_t get_max_fw_size(void)
>  {
>      Object *m_obj = qdev_get_machine();
> -    PCMachineState *pcms = PC_MACHINE(m_obj);
> +    MachineState *ms = MACHINE(m_obj);
> +    PCMachineState *pcms;
> -    if (pcms) {
> +    if (object_dynamic_cast(OBJECT(ms), TYPE_X86_MACHINE)) {
> +        pcms = PC_MACHINE(m_obj);
>          return pcms->max_fw_size;
>      } else {
>          return 0;
>

For the records, I tested this with arm and the following command line
does not crash QEMU;

./qemu-system-arm -machine virt-9.2 -device vmfwupdate

I have also added a separate functional test to exercise basic device
creation which will be part of v5 when I send it out.