> -----Original Message----- > From: Ananyev, Konstantin > Sent: Tuesday, May 26, 2015 11:46 PM > To: Stephen Hemminger > Cc: Zhang, Helin; dev at dpdk.org > Subject: RE: [dpdk-dev] [PATCH 2/5] mbuf: use the reserved 16 bits for > double vlan > > > > > -----Original Message----- > > From: Stephen Hemminger [mailto:stephen at networkplumber.org] > > Sent: Tuesday, May 26, 2015 4:35 PM > > To: Ananyev, Konstantin > > Cc: Zhang, Helin; dev at dpdk.org > > Subject: Re: [dpdk-dev] [PATCH 2/5] mbuf: use the reserved 16 bits for > > double vlan > > > > On Tue, 26 May 2015 15:02:51 +0000 > > "Ananyev, Konstantin" <konstantin.ananyev at intel.com> wrote: > > > > > Hi Stephen, > > > > > > > -----Original Message----- > > > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Stephen > > > > Hemminger > > > > Sent: Tuesday, May 26, 2015 3:55 PM > > > > To: Zhang, Helin > > > > Cc: dev at dpdk.org > > > > Subject: Re: [dpdk-dev] [PATCH 2/5] mbuf: use the reserved 16 bits > > > > for double vlan > > > > > > > > On Tue, 26 May 2015 16:36:37 +0800 Helin Zhang > > > > <helin.zhang at intel.com> wrote: > > > > > > > > > Use the reserved 16 bits in rte_mbuf structure for the outer > > > > > vlan, also add QinQ offloading flags for both RX and TX sides. > > > > > > > > > > Signed-off-by: Helin Zhang <helin.zhang at intel.com> > > > > > > > > Yet another change that is much needed, but breaks ABI > compatibility. > > > > > > Why do you think it breaks ABI compatibility? > > > As I can see, it uses field that was reserved. > > > Konstantin > > > > Because an application maybe assuming something or reusing the > reserved fields. > > But properly behaving application, shouldn't do that right? > And for misbehaving ones, why should we care about them? For any reserved bits, I think all application users should avoid touching it, as it is reserved for future use, or some special reason. Otherwise, un-predicted behavior can be expected.
Regards, Helin > > > Yes, it would be dumb of application to do that but from absolute ABI > > point of view it is a change. > > So, in theory, even adding a new field to the end of rte_mbuf is an ABI > breakage? > Konstantin
