[Qemu-devel] Re: [PATCH] e1000: Pad short frames to minimum size (60 bytes)

["Michael S. Tsirkin" <mst@redhat.com>]

On Sat, Sep 18, 2010 at 09:43:45PM +0100, Stefan Hajnoczi wrote:
> The OpenIndiana (Solaris) e1000g driver drops frames that are too long
> or too short.  It expects to receive frames of at least the Ethernet
> minimum size.  ARP requests in particular are small and will be dropped
> if they are not padded appropriately, preventing a Solaris VM from
> becoming visible on the network.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

I'll put this patch on my tree: let's be consistent and fix e1000,
it is also a good approach for 0.13 I think.
Anthony - could you pick this up for 0.13 please?
If someone wants to then strip it off from all devices and tweak, it can
be done.

> ---
>  hw/e1000.c |   10 ++++++++++
>  1 files changed, 10 insertions(+), 0 deletions(-)
> 
> diff --git a/hw/e1000.c b/hw/e1000.c
> index 7d7d140..bc983f9 100644
> --- a/hw/e1000.c
> +++ b/hw/e1000.c
> @@ -55,6 +55,7 @@ static int debugflags = DBGBIT(TXERR) | DBGBIT(GENERAL);
>  
>  #define IOPORT_SIZE       0x40
>  #define PNPMMIO_SIZE      0x20000
> +#define MIN_BUF_SIZE      60
>  
>  /*
>   * HW models:
> @@ -635,10 +636,19 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size)
>      uint32_t rdh_start;
>      uint16_t vlan_special = 0;
>      uint8_t vlan_status = 0, vlan_offset = 0;
> +    uint8_t min_buf[MIN_BUF_SIZE];
>  
>      if (!(s->mac_reg[RCTL] & E1000_RCTL_EN))
>          return -1;
>  
> +    /* Pad to minimum Ethernet frame length */
> +    if (size < sizeof(min_buf)) {
> +        memcpy(min_buf, buf, size);
> +        memset(&min_buf[size], 0, sizeof(min_buf) - size);
> +        buf = min_buf;
> +        size = sizeof(min_buf);
> +    }
> +
>      if (size > s->rxbuf_size) {
>          DBGOUT(RX, "packet too large for buffers (%lu > %d)\n",
>                 (unsigned long)size, s->rxbuf_size);
> -- 
> 1.7.1
>