Re: Ethernet Checksum

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In e1000_main.c , I changed , 
 
skb_put(skb, length - ETHERNET_FCS_SIZE); , to 

skb_put(skb, length); 

In effect I caprured the last four bytes. 
I was also able to see the "TRAILER"
 field on ethereal. 

Thanks a lot!
Sai 






--- warrier@xxxxxxxxxxx wrote:
> Well yes. I prefer to call them buffer descriptors. 
> I haven't looked at 
> your chip's details . However some chips may not
> tell you the amount of 
> data transferred. In that case you would be better
> off looking at the 
> length field which would be 12 bytes from the
> begining of the buffer (DA(6 
> bytes) + SA( 6 bytes).  The last driver I  modified
> wrote the number of 
> bytes transferred including the  four bytes of CRC,
> into the Rxbd, after 
> the DMA was complete.
>  I don't know what your chip does, but the manual
> should have the details. 
> 
> 
> S
> 
> 
> 
> 
> sai narasimhamurthy <sai_narasi@xxxxxxxxx>
> Sent by: linux-net-owner@xxxxxxxxxxxxxxx
> 05/03/2005 11:37 PM
> 
>  
>         To:     warrier@xxxxxxxxxxx
>         cc:     linux-net@xxxxxxxxxxxxxxx
>         Subject:        Re: Ethernet Checksum
> 
> 
> I am thinking that you are referring to the RX ring
> buffers(given below)  ...when you said rx buffer
> descriptor .....
> Thanks
> Sai
> 
> 
> 161 struct e1000_desc_ring {
> 162         /* pointer to the descriptor ring memory
> */
> 163         void *desc;
> 164         /* physical address of the descriptor
> ring
> */
> 165         dma_addr_t dma;
> 166         /* length of descriptor ring in bytes */
> 167         unsigned int size;
> 168         /* number of descriptors in the ring */
> 169         unsigned int count;
> 170         /* next descriptor to associate a buffer
> with */
> 171         unsigned int next_to_use;
> 172         /* next descriptor to check for DD
> status
> bit */
> 173         unsigned int next_to_clean;
> 174         /* array of buffer information structs
> */
> 175         struct e1000_buffer *buffer_info;
> 176 };
> 
> 
> 
>
================================================================
> 
> 
> 
> --- warrier@xxxxxxxxxxx wrote:
> > I'm not too sure about this but  most chipsets
> write
> > the received CRC at 
> > the end of the data buffer. You may want to dump
> the
> > data as soon as you 
> > get an rx interrupt. The length in the rx buffer
> > descriptor should tell 
> > you where the data ends. The next four bytes
> should
> > be the CRC. I think 
> > ethereal may ignore this and only look at the data
> > length.
> > 
> > S
> > 
> > 
> > 
> > 
> > sai narasimhamurthy <sai_narasi@xxxxxxxxx>
> > Sent by: linux-net-owner@xxxxxxxxxxxxxxx
> > 05/03/2005 05:52 PM
> > 
> > 
> >         To: 
> >         cc: 
> >         Subject:        Ethernet Checksum
> > 
> > 
> > I have an application which requires the recieved
> > ethernet checksum. To begin with, I need to see if
> > the
> > ethernet checksum can be accessed at all. I was
> not
> > able to view  it in ethereal.
> > 
> > How can I get access(or atleast get to see) the
> > ethernet checksum at the reciever? 
> > 
> > I am in linux 2.4.29 , am using intel 82546 GBE. 
> > 
> > Sai 
> > 
> > 
> > 
> > 
> > 
> > __________________________________ 
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