Thanks for taking time reviewing it, my reply is inline. ----- Original Message ----- From: David Edmondson <[EMAIL PROTECTED]> Date: Monday, July 17, 2006 9:53 pm Subject: Re: [networking-discuss] Promiscuous DLPI packet loopback (was something else) To: Dong-Hai Han <[EMAIL PROTECTED]> Cc: networking-discuss@opensolaris.org
> > On 11 Jul 2006, at 3:57pm, Dong-Hai Han wrote: > > I am posting the materials Mike mentioned earlier, the webrev of > > the changes is: > > http://www.omnicron.com/~ford/webrev_bridging_dlpi.premacplugin/ > > I've taken a quick look at this and, as you know, have incorporated > a > previous version of the code into the gate for the Matrix project[1]. > > The general approach seems workable, but I think that the details > have to be right. For example, i_dl_txloop() assumes that a MAC > driver will consume either all or none of the packets passed to it: > > 263 /* > 264 * Transmit function, used when the link is doing local loopback > 265 */ > 266 static mblk_t * > 267 i_dls_txloop(dls_impl_t *dip, mblk_t *mp) > 268 { > 269 const mac_txinfo_t *mtp = dip->di_txinfo; > 270 dls_link_t *dlp = dip->di_dvp->dv_dlp; > 271 mblk_t *nextp; > 272 mblk_t *bp; > 273 > 274 while (mp != NULL) { > 275 nextp = mp->b_next; > 276 mp->b_next = NULL; > 277 > 278 dlp->dl_local_loopback(dip->di_dvp->dv_dlp, mp, > > dip); > 279 > 280 if ((bp = mtp->mt_fn(mtp->mt_arg, mp)) != NULL) { > 281 ASSERT(bp == mp); > 282 goto noresources; > 283 } > 284 > 285 mp = nextp; > 286 } > 287 > 288 return (NULL); > 289 > 290 noresources: > 291 mp->b_next = nextp; > 292 return (mp); > 293 } > 294 > > (Note lines 280/281.) > > Quick inspection of the Broadcom driver shows that it's entirely > possible that the MAC driver's transmit routine will accept some > but > not all of the packets passed down. i_dls_txloop() needs to allow > for this. Meem has pointed out what's happening here, thanks Meem. > > It's also the case that this newer version of the code will > loopback > packets that are not accepted for transmission by the MAC driver > (the > loopback happens before the packets are passed down). This differs > > from the older code, where the loopback occurred only if the MAC > driver accepted the packets. Yes, it's changed. Mike and I have dicussed it, our conclusion is that: 1. Even if MAC driver returns OK, it doesn't mean that the packet is safe on the line, or even being sent out. 2. For xen case, when domUs are communicating with each other, does it make sense to cut the virtual link when the packet can't go through the physical link? So, we chose this approach. > > [1] http://www.opensolaris.org/os/community/xen. > > dme. > > Best, Donghai. _______________________________________________ networking-discuss mailing list networking-discuss@opensolaris.org
