Re: [Qemu-devel] [RFC PATCH v2 1/5] net: macaddr tweaks.

[Anthony Liguori <anthony@codemonkey.ws>]

Gerd Hoffmann wrote:
> Add new type for mac addresses.
>
> Add function which sets the qemu default mac address if it finds the mac
> address uninitialized (i.e. all zeros).
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  net.c |   15 +++++++++++++++
>  net.h |    2 ++
>  2 files changed, 17 insertions(+), 0 deletions(-)
>
> diff --git a/net.c b/net.c
> index 2e4dd58..4dc910b 100644
> --- a/net.c
> +++ b/net.c
> @@ -281,6 +281,21 @@ void qemu_format_nic_info_str(VLANClientState *vc, uint8_t macaddr[6])
>               macaddr[3], macaddr[4], macaddr[5]);
>  }
>  
> +void qemu_macaddr_default_if_unset(macaddr_t macaddr)
> +{
> +    static int index = 0;
> +    static const macaddr_t zero = { 0,0,0,0,0,0 };
> +
> +    if (memcmp(macaddr, zero, sizeof(zero)) != 0)
> +        return;
> +    macaddr[0] = 0x52;
> +    macaddr[1] = 0x54;
> +    macaddr[2] = 0x00;
> +    macaddr[3] = 0x12;
> +    macaddr[4] = 0x34;
> +    macaddr[5] = 0x56 + index++;
> +}
> +
>  static char *assign_name(VLANClientState *vc1, const char *model)
>  {
>      VLANState *vlan;
> diff --git a/net.h b/net.h
> index 2b0ed9b..7aefc51 100644
> --- a/net.h
> +++ b/net.h
> @@ -8,6 +8,7 @@
>  
>  /* VLANs support */
>  
> +typedef uint8_t macaddr_t[6];
>   

Let's make it a stronger type and avoid introducing more _t types.  I'd 
suggest:

typedef struct MacAddress
{
    uint8_t addr[6];
} MacAddress

>  typedef struct VLANClientState VLANClientState;
>  
>  typedef int (NetCanReceive)(VLANClientState *);
> @@ -76,6 +77,7 @@ ssize_t qemu_send_packet_async(VLANClientState *vc, const uint8_t *buf,
>  void qemu_purge_queued_packets(VLANClientState *vc);
>  void qemu_flush_queued_packets(VLANClientState *vc);
>  void qemu_format_nic_info_str(VLANClientState *vc, uint8_t macaddr[6]);
> +void qemu_macaddr_default_if_unset(macaddr_t macaddr);
>   

Couldn't we set the default based on a qdev default property?  A #define 
could be used to ensure there was a global default.

Regards,

Anthony Liguori