[dpdk-dev] Who can correct me about 82599 RSS Hash Function

[chen_lp at neusoft.com]

I want calculate the NIC rss hash result by function,but the result is not right, I don't know where the wrong.


struct mbf_cb{
        uint32_t sip;
        uint32_t dip;
        uint16_t sport;
        uint16_t dport;
};

static uint8_t test_rss[]={
        0x6d,0x5a,0x56,0xda,0x25,0x5b,0x0e,0xc2,
        0x41,0x67,0x25,0x3d,0x43,0xa3,0x8f,0xb0,
        0xd0,0xca,0x2b,0xcb,0xae,0x7b,0x30,0xb4,
        0x77,0xcb,0x2d,0xa3,0x80,0x30,0xf2,0x0c,
        0x6a,0x42,0xb7,0x3b,0xbe,0xac,0x01,0xfa,
};

static uint8_t input_mask[]={
        0x01,0x02,0x04,0x08,
        0x10,0x20,0x40,0x80,
};

 mcb.sip=rte_cpu_to_be_32(IPv4(66,9,149,187));
  mcb.dip=rte_cpu_to_be_32(IPv4(161,142,100,80));
   mcb.sport=rte_cpu_to_be_16(2794);
   mcb.dport=rte_cpu_to_be_16(1766);


uint32_t compute_hash(uint8_t *input, int n)
{
        int i,j,k;
        uint32_t result=0;
        uint32_t *lk;
        uint8_t rss_key[40];

        memcpy(rss_key,test_rss,40);

        lk=(uint32_t *)rss_key;
        for(i=0;i<n;i++){
                for(j=0;j<8;j++){
                        if((input_mask[j])&input[i]){
                                result^=*lk;
                        }

                        // shift k left 1 bit
                        rss_key[0]=rss_key[0]<<1;
                        for(k=1;k<40;k++){
                                if(rss_key[k]&0x80){
                                        rss_key[k-1]|=0x01;
                                }
                                rss_key[k]=rss_key[k]<<1;
                        }
                }
        }
        return result;
}

printf("rss_hash=%#x\n",compute_hash((uint8_t *)&mcb,sizeof(struct mbf_cb)));

rss_hash=0x57476eca
 but the right result is 0x51ccc178







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