Subject: Re: tcp/udp vector h/w checksum
To: None <>
From: YAMAMOTO Takashi <>
List: tech-net
Date: 02/06/2005 05:09:50

> I can see your problem, but I think your patch breaks the (intended)
> existing semantics of M_CSUM_NO_PSEUDOHDR.
> The gotcha is that we support hardware, e.g., bge(4), which implements
> a full normal IPv4 checksum on outbound traffic, but does only the
> no-pseudoheader on received traffic.  (That's a defensible choice for,
> e.g., summing fragmented large IP datagrams).  And we really don't
> want to do the Tx-no-phdr work in cases where we don't have to.  (I
> wasn't aware of the hme/gem hardware, or just wasn't thinking clearly,
> when I implemented the x-side no-phdr flag we have.)
> changes, but I can't get to bge hardware until Monday.

bge doesn't have to set M_CSUM_NO_PSEUDOHDR in if_csum_flags_tx.
what's a problem?