Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, May 13, 2015 at 06:29:46PM +0100, Stefano Stabellini wrote:
> Do not emulate a floppy drive if no drives are supposed to be present.
> 
> This fixes the behavior of -nodefaults, that should remove the floppy
> drive (see docs/qdev-device-use.txt:Default Devices), but actually
> doesn't.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

No telling what this might break.  I think a flag or a property to
disable fdc would be safer. Default to enabled to make sure we
don't break existing users.

> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index a8e6be1..c9f50b3 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1410,6 +1410,7 @@ void pc_basic_device_init(ISABus *isa_bus, qemu_irq *gsi,
>      qemu_irq *cpu_exit_irq;
>      MemoryRegion *ioport80_io = g_new(MemoryRegion, 1);
>      MemoryRegion *ioportF0_io = g_new(MemoryRegion, 1);
> +    bool floppy_exist;
>  
>      memory_region_init_io(ioport80_io, NULL, &ioport80_io_ops, NULL, "ioport80", 1);
>      memory_region_add_subregion(isa_bus->address_space_io, 0x80, ioport80_io);
> @@ -1487,10 +1488,17 @@ void pc_basic_device_init(ISABus *isa_bus, qemu_irq *gsi,
>      cpu_exit_irq = qemu_allocate_irqs(cpu_request_exit, NULL, 1);
>      DMA_init(0, cpu_exit_irq);
>  
> +    *floppy = NULL;
> +    floppy_exist = false;
>      for(i = 0; i < MAX_FD; i++) {
>          fd[i] = drive_get(IF_FLOPPY, 0, i);
> +        if (fd[i] != NULL) {
> +            floppy_exist = true;
> +        }
> +    }
> +    if (floppy_exist) {
> +        *floppy = fdctrl_init_isa(isa_bus, fd);
>      }
> -    *floppy = fdctrl_init_isa(isa_bus, fd);
>  }
>  
>  void pc_nic_init(ISABus *isa_bus, PCIBus *pci_bus)