RE: [PATCH] hw/i386/xen: Remove dead code

[Paul Durrant <xadimgnik@gmail.com>]

> -----Original Message-----
> From: Philippe Mathieu-Daudé <philmd@redhat.com>
> Sent: 02 February 2021 15:57
> To: qemu-devel@nongnu.org
> Cc: Richard Henderson <richard.henderson@linaro.org>; Paolo Bonzini <pbonzini@redhat.com>; Eduardo
> Habkost <ehabkost@redhat.com>; qemu-trivial@nongnu.org; Michael S. Tsirkin <mst@redhat.com>; Marcel
> Apfelbaum <marcel.apfelbaum@gmail.com>; xen-devel@lists.xenproject.org; Paul Durrant <paul@xen.org>;
> Anthony Perard <anthony.perard@citrix.com>; Stefano Stabellini <sstabellini@kernel.org>; Philippe
> Mathieu-Daudé <philmd@redhat.com>
> Subject: [PATCH] hw/i386/xen: Remove dead code
> 
> 'drivers_blacklisted' is never accessed, remove it.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

FTR this is a vestige of an ancient mechanism that's not used any more (see https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/misc/hvm-emulated-unplug.pandoc step 5).

Reviewed-by: Paul Durrant <paul@xen.org>

> ---
>  hw/i386/xen/xen_platform.c | 13 ++-----------
>  1 file changed, 2 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/i386/xen/xen_platform.c b/hw/i386/xen/xen_platform.c
> index 7c4db35debb..01ae1fb1618 100644
> --- a/hw/i386/xen/xen_platform.c
> +++ b/hw/i386/xen/xen_platform.c
> @@ -60,7 +60,6 @@ struct PCIXenPlatformState {
>      MemoryRegion bar;
>      MemoryRegion mmio_bar;
>      uint8_t flags; /* used only for version_id == 2 */
> -    int drivers_blacklisted;
>      uint16_t driver_product_version;
> 
>      /* Log from guest drivers */
> @@ -245,18 +244,10 @@ static void platform_fixed_ioport_writeb(void *opaque, uint32_t addr, uint32_t v
> 
>  static uint32_t platform_fixed_ioport_readw(void *opaque, uint32_t addr)
>  {
> -    PCIXenPlatformState *s = opaque;
> -
>      switch (addr) {
>      case 0:
> -        if (s->drivers_blacklisted) {
> -            /* The drivers will recognise this magic number and refuse
> -             * to do anything. */
> -            return 0xd249;
> -        } else {
> -            /* Magic value so that you can identify the interface. */
> -            return 0x49d2;
> -        }
> +        /* Magic value so that you can identify the interface. */
> +        return 0x49d2;
>      default:
>          return 0xffff;
>      }
> --
> 2.26.2