On Mon, 26 Aug 2019 18:25:10 +0200, Daniel Borkmann wrote: > On 8/26/19 6:18 PM, Alexei Starovoitov wrote: > > On Mon, Aug 26, 2019 at 8:57 AM Jakub Kicinski > > <jakub.kicinski@xxxxxxxxxxxxx> wrote: > >> On Sun, Aug 25, 2019 at 10:37 PM Song Liu <liu.song.a23@xxxxxxxxx> wrote: > >>> On Fri, Aug 23, 2019 at 7:04 PM Jakub Kicinski wrote: > >>>> From: Jiong Wang <jiong.wang@xxxxxxxxxxxxx> > >>>> > >>>> NFP is using Local Memory to model stack. LM_addr could be used as base of > >>>> a 16 32-bit word region of Local Memory. Then, if the stack offset is > >>>> beyond the current region, the local index needs to be updated. The update > >>>> needs at least three cycles to take effect, therefore the sequence normally > >>>> looks like: > >>>> > >>>> local_csr_wr[ActLMAddr3, gprB_5] > >>>> nop > >>>> nop > >>>> nop > >>>> > >>>> If the local index switch happens on a narrow loads, then the instruction > >>>> preparing value to zero high 32-bit of the destination register could be > >>>> counted as one cycle, the sequence then could be something like: > >>>> > >>>> local_csr_wr[ActLMAddr3, gprB_5] > >>>> nop > >>>> nop > >>>> immed[gprB_5, 0] > >>>> > >>>> However, we have zero extension optimization that zeroing high 32-bit could > >>>> be eliminated, therefore above IMMED insn won't be available for which case > >>>> the first sequence needs to be generated. > >>>> > >>>> Fixes: 0b4de1ff19bf ("nfp: bpf: eliminate zero extension code-gen") > >>>> Signed-off-by: Jiong Wang <jiong.wang@xxxxxxxxxxxxx> > >>>> Reviewed-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx> > >>> I haven't looked into the code yet. But ^^^ should be > >>> > >>> Signed-off-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx> > >>> > >>> right? > >> > >> I prefer Review on code I review, ack on code I ack, and sign-off on > >> code I co-author. > > > > I believe if you're sending somebody else patch you have to add your SOB > > in addition to their 'Author:' and their SOB fields. > > +1, for co-authoring there's a 'Co-authored-by:' tag which seems to be frequently > used these days. Ack, there is a difference between co-author of code, and co-author as step by step guidance. I've been doing this for 6 years now, and nobody ever complained :) Signed-off-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx> Is that enough or should I repost?