Re: [PATCH 2/5] Introduce constant MAC_BROADCAST

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Sep 16, 2025 at 09:21:13PM +0200, Volker Diels-Grabsch wrote:
> Signed-off-by: Volker Diels-Grabsch <v@njh.eu>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  tap.c  | 2 +-
>  util.h | 2 ++
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tap.c b/tap.c
> index cf862ef..50e1a88 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -1511,7 +1511,7 @@ void tap_backend_init(struct ctx *c)
>  		 * sends us packets.  Use the broadcast address so that our
>  		 * first packets will reach it.
>  		 */
> -		memset(&c->guest_mac, 0xff, sizeof(c->guest_mac));
> +		memcpy(&c->guest_mac, MAC_BROADCAST, sizeof(c->guest_mac));
>  		break;
>  	}
>  
> diff --git a/util.h b/util.h
> index 2a8c38f..22eaac5 100644
> --- a/util.h
> +++ b/util.h
> @@ -97,6 +97,8 @@ void abort_with_msg(const char *fmt, ...)
>  #define FD_PROTO(x, proto)						\
>  	(IN_INTERVAL(c->proto.fd_min, c->proto.fd_max, (x)))
>  
> +#define MAC_BROADCAST							\
> +	((uint8_t [ETH_ALEN]){ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff })
>  #define MAC_ZERO		((uint8_t [ETH_ALEN]){ 0 })
>  #define MAC_IS_ZERO(addr)	(!memcmp((addr), MAC_ZERO, ETH_ALEN))
>  
> -- 
> 2.47.3
> 

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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