[Xen-devel] Re: skb_checksum_setup() placement in pv-ops vs. legacy kernel

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 03.12.10 at 14:18, Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx> wrote:
> The setup which is done in skb_checksum_setup is internal to the guest's
> skb data structure and doesn't cross the pv interface boundary. The
> fields which it sets up are just offsets to the checksum field in the
> packet, it doesn't actually manipulate the content of the packet or
> impact what goes into the ring until/unless the guest does TSO or
> something similar in which case the kernel needs to make sure the fields
> are setup first.

Okay, that makes it much easier to change the behavior then.

What I'm then not understanding is who the consumer of this
data is, and why it wasn't done the receive path way from the
beginning. Were there issues with the no longer used loopback
driver? Or did kernel networking infrastructure change (if so,
it'd be nice to know when and what)?

Thanks for bearing with me,
Jan


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