Re: [Qemu-devel] [PATCH] eepro100: Fix multicast regression

[Michael S. Tsirkin]

On Tue, Apr 10, 2012 at 08:48:54PM +0200, Stefan Weil wrote:
> Commit 7fc8d918b9674c3e9233d6d25da2457345d414a0 removed code from
> eepro100.c and replaced it by different code: the code in net.c
> returns bits 31...26, but eepro100 needs bits 7...2.
> 
> This patch partially reverts 7fc8d918b9674c3e9233d6d25da2457345d414a0.
> To avoid future problems, I renamed the function and changed the comment.
> 
> Cc: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Stefan Weil <address@hidden>

Cc Jason who wrote this originally.

> ---
>  hw/eepro100.c |   28 ++++++++++++++++++++++++++--
>  1 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/eepro100.c b/hw/eepro100.c
> index 02e6f7e..6279ae3 100644
> --- a/hw/eepro100.c
> +++ b/hw/eepro100.c
> @@ -322,8 +322,32 @@ static const uint16_t eepro100_mdi_mask[] = {
>      0xffff, 0xffff, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
>  };
>  
> +#define POLYNOMIAL 0x04c11db6
> +
>  static E100PCIDeviceInfo *eepro100_get_class(EEPRO100State *s);
>  
> +/* From FreeBSD (locally modified). */
> +static unsigned e100_compute_mcast_idx(const uint8_t *ep)
> +{
> +    uint32_t crc;
> +    int carry, i, j;
> +    uint8_t b;
> +
> +    crc = 0xffffffff;
> +    for (i = 0; i < 6; i++) {
> +        b = *ep++;
> +        for (j = 0; j < 8; j++) {
> +            carry = ((crc & 0x80000000L) ? 1 : 0) ^ (b & 0x01);
> +            crc <<= 1;
> +            b >>= 1;
> +            if (carry) {
> +                crc = ((crc ^ POLYNOMIAL) | carry);
> +            }
> +        }
> +    }
> +    return (crc & BITS(7, 2)) >> 2;
> +}
> +
>  /* Read a 16 bit control/status (CSR) register. */
>  static uint16_t e100_read_reg2(EEPRO100State *s, E100RegisterOffset addr)
>  {
> @@ -823,7 +847,7 @@ static void set_multicast_list(EEPRO100State *s)
>          uint8_t multicast_addr[6];
>          pci_dma_read(&s->dev, s->cb_address + 10 + i, multicast_addr, 6);
>          TRACE(OTHER, logout("multicast entry %s\n", nic_dump(multicast_addr, 
> 6)));
> -        unsigned mcast_idx = compute_mcast_idx(multicast_addr);
> +        unsigned mcast_idx = e100_compute_mcast_idx(multicast_addr);
>          assert(mcast_idx < 64);
>          s->mult[mcast_idx >> 3] |= (1 << (mcast_idx & 7));
>      }
> @@ -1650,7 +1674,7 @@ static ssize_t nic_receive(VLANClientState *nc, const 
> uint8_t * buf, size_t size
>          if (s->configuration[21] & BIT(3)) {
>            /* Multicast all bit is set, receive all multicast frames. */
>          } else {
> -          unsigned mcast_idx = compute_mcast_idx(buf);
> +          unsigned mcast_idx = e100_compute_mcast_idx(buf);
>            assert(mcast_idx < 64);
>            if (s->mult[mcast_idx >> 3] & (1 << (mcast_idx & 7))) {
>              /* Multicast frame is allowed in hash table. */
> -- 
> 1.7.9