Re: [PATCH for 6.2?] Revert "vga: don't abort when adding a duplicate isa-vga device"

[Cornelia Huck]

On Thu, Dec 02 2021, Alex Bennée <alex.bennee@linaro.org> wrote:

> This reverts commit 7852a77f598635a67a222b6c1463c8b46098aed2.
>
> The check is bogus as it ends up finding itself and falling over.
>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Resolves: https://gitlab.com/qemu-project/qemu.git/-/issues/733
> ---
>  hw/display/vga-isa.c | 10 ----------
>  1 file changed, 10 deletions(-)
>
> diff --git a/hw/display/vga-isa.c b/hw/display/vga-isa.c
> index 8cea84f2be..90851e730b 100644
> --- a/hw/display/vga-isa.c
> +++ b/hw/display/vga-isa.c
> @@ -33,7 +33,6 @@
>  #include "hw/loader.h"
>  #include "hw/qdev-properties.h"
>  #include "qom/object.h"
> -#include "qapi/error.h"
>  
>  #define TYPE_ISA_VGA "isa-vga"
>  OBJECT_DECLARE_SIMPLE_TYPE(ISAVGAState, ISA_VGA)
> @@ -62,15 +61,6 @@ static void vga_isa_realizefn(DeviceState *dev, Error 
> **errp)
>      MemoryRegion *vga_io_memory;
>      const MemoryRegionPortio *vga_ports, *vbe_ports;
>  
> -    /*
> -     * make sure this device is not being added twice, if so
> -     * exit without crashing qemu
> -     */
> -    if (object_resolve_path_type("", TYPE_ISA_VGA, NULL)) {

Don't you simply need to invert the check? You should get NULL back if
there is another device already...

> -        error_setg(errp, "at most one %s device is permitted", TYPE_ISA_VGA);
> -        return;
> -    }
> -
>      s->global_vmstate = true;
>      vga_common_init(s, OBJECT(dev));
>      s->legacy_address_space = isa_address_space(isadev);