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

[Mark Cave-Ayland]

On 02/12/2021 17:14, Cornelia Huck wrote:

> 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...

Yes that's correct - the existing check is simply missing a ! at the front. For an 
existing example take a look at the the fw_cfg device:

https://gitlab.com/qemu-project/qemu/-/blob/master/hw/nvram/fw_cfg.c#L1228
https://gitlab.com/qemu-project/qemu/-/blob/master/hw/nvram/fw_cfg.c#L1125

Unfortunately it seems that I also missed this when I added my R-B tag :(


ATB,

Mark.