Re: igb mtu change

On 10/17/2012 07:41 AM, ratheesh kannoth wrote:

igb_change_mtu change is only changing adapter->rx_ring[0]->rx_buffer_len.

1)  we dont have to change adapter->tx_ring[0]->rx_buffer_len ?
2) Is there any way to set different values to
adapter->tx_ring[0]->rx_buffer_len and
adapter->rx_ring[0]->rx_buffer_len ?

I am facing a problem because i have a strange requirement....i have
2KB  bufffer pools ( GFP_DMA ) in kernel.
When i receive a jumbo pkt of size 9126,     five rx_desc should be
used to recieve paket. So the first rx_desc will have a status error
bit indicating that it is not
EOP ( eop ) ....I could easily keep track of my 2KB buffer pools.

But when sending ...i wll collect all  2KB buffers of same jumbo frame
and dma to tx_ring....
So i need  1500  on rx_ring[0]->rx_buffer_len and  9126 on
adapter->tx_ring[0]->rx_buffer_len. .Is there any way ?

Thanks,
Ratheesh

What version of the igb driver are you using?  What you are describing
doesn't sound like the behaviour of the current igb driver.

The current igb driver does receive the frame data into 2K buffers, and
transmits up to MTU size.  The only limitation on the size of the frame
you can transmit is the netdev->mtu which the driver doesn't evaluate. 
It is evaluated at the network stack level.  The igb driver can send up
to 9K frames, in addition it can TSO up to 64K frames and send them in
9K chunks so I am not sure what you are asking.

Thanks,

Alex