Re: [PATCH] vga: don't abort when adding a duplicate isa-vga device

[Thomas Huth <thuth@redhat.com>]

On 14/08/2021 01.36, Jose R. Ziviani wrote:
> If users try to add an isa-vga device that was already registered,
> still in command line, qemu will crash:
> 
> $ qemu-system-mips64el -M pica61 -device isa-vga
> RAMBlock "vga.vram" already registered, abort!
> Aborted (core dumped)
> 
> That particular board registers such device automaticaly, so it's
> not obvious that a VGA device already exists. This patch changes
> this behavior by displaying a message and ignoring that device,
> starting qemu normally.
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/44
> Signed-off-by: Jose R. Ziviani <jziviani@suse.de>
> ---
>   hw/display/vga-isa.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/hw/display/vga-isa.c b/hw/display/vga-isa.c
> index 90851e730b..69db502dde 100644
> --- a/hw/display/vga-isa.c
> +++ b/hw/display/vga-isa.c
> @@ -61,6 +61,15 @@ static void vga_isa_realizefn(DeviceState *dev, Error **errp)
>       MemoryRegion *vga_io_memory;
>       const MemoryRegionPortio *vga_ports, *vbe_ports;
>   
> +    /*
> +     * some machines register VGA by default, so instead of aborting
> +     * it, show a message and ignore this device.
> +     */
> +    if (qemu_ram_block_by_name("vga.vram")) {
> +        error_report("vga.vram is already registered, ignoring this device");
> +        return;
> +    }

I think we should not ignore the error, but rather turn this into a proper 
error (instead of aborting).

So if you replace error_report(...) with error_setg(errp, ...), the patch 
should be fine.

  Thomas