Re: kern/53562: bridge(4) breaks segmentation / TX checksum offloading

[Rin Okuyama <rokuyama%rk.phys.keio.ac.jp@localhost>]

The following reply was made to PR kern/53562; it has been noted by GNATS.

From: Rin Okuyama <rokuyama%rk.phys.keio.ac.jp@localhost>
To: Masanobu SAITOH <msaitoh%execsw.org@localhost>, gnats-bugs%NetBSD.org@localhost,
 kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/53562: bridge(4) breaks segmentation / TX checksum
 offloading
Date: Sun, 16 Sep 2018 22:49:24 +0900

 On 2018/09/14 20:17, Masanobu SAITOH wrote:
 > On 2018/09/12 21:33, Rin Okuyama wrote:
 ...
 >> This patch disable TX offload when the interface is added to bridge:
 >>
 >> http://www.netbsd.org/~rin/disable_tx_offload_when_bridged_20180912.patch
 > 
 > I don't know if it's good to doing in L3...
 > 
 > It seems that both FreeBSD and DragonFly clear all bridge member's outgoing
 > offload flags when adding a member to a bridge. I also don't know if
 > this is good solution or not...
 
 If I understand correctly, since TX offload is for L3 (and L4), we
 inevitably need something to do in L3...
 
 I implemented software TX/RX offload engines for ethernet:
 
    http://www.netbsd.org/~rin/ether_offload_20180916.patch
 
 Using these routines, I wrote a patch where TX offloading is canceled in
 bridge_output() when the destination interface is different from the
 source interface:
 
    http://www.netbsd.org/~rin/bridge_tx_offload_20180916.patch
 
 With this patch, the guest successfully communicates with the host even
 if any TX offloading is enabled on the host side.
 
 Also, I added TX/RX offloading support to shmif(4):
 
    http://www.netbsd.org/~rin/shmif_offload_20180916.patch
 
 Since I'm not familiar with rump, this patch has not been tested
 systematically yet. But it seems to work to some extent...
 
 Thanks,
 rin