Florian Westphal <fw@xxxxxxxxx> wrote: > Brian Davidson <davidson.brian@xxxxxxxxx> wrote: > > Using 'ip6 dscp' in a map lookup does not give expected results. It > > seems to always match the zero value (cs0). It appears in the first > > rule that the byteorder is not being converted between the two bitwise > > operations, which is what happens when using ip6 dscp directly in the > > second rule. > > > > # nft -f - <<EOF > > add table ip6 t > > add chain ip6 t c > > add map ip6 t mapv6 { typeof ip6 dscp : meta mark; } > > EOF > > > > # nft -d netlink add rule ip6 t c meta mark set ip6 dscp map @mapv6 > > ip6 t c > > [ payload load 2b @ network header + 0 => reg 1 ] > > [ bitwise reg 1 = ( reg 1 & 0x0000c00f ) ^ 0x00000000 ] > > [ bitwise reg 1 = ( reg 1 >> 0x00000006 ) ] > > [ lookup reg 1 set mapv6 dreg 1 ] > > [ meta set mark with reg 1 ] > > > > # nft -d netlink add rule ip6 t c meta mark set ip6 dscp > > ip6 t c > > [ payload load 2b @ network header + 0 => reg 1 ] > > [ bitwise reg 1 = ( reg 1 & 0x0000c00f ) ^ 0x00000000 ] > > [ byteorder reg 1 = ntoh(reg 1, 2, 2) ] > > [ bitwise reg 1 = ( reg 1 >> 0x00000006 ) ] > > [ meta set mark with reg 1 ] > > Uhm. Pablo, any idea why the byte-swap-or-not logic depends > on something *other* than if the mask length is > 8 bit or not? > > diff --git a/src/evaluate.c b/src/evaluate.c > --- a/src/evaluate.c > +++ b/src/evaluate.c > @@ -545,7 +545,7 @@ static void expr_evaluate_bits(struct eval_ctx *ctx, struct expr **exprp) > and->len = masklen; > > if (shift) { > - if (ctx->stmt_len > 0 && div_round_up(masklen, BITS_PER_BYTE) > 1) { > + if (masklen > BITS_PER_BYTE) { I think this is right but binop xfer won't remove the inserted byteorder conversion in case the shift is to be removed by adjusting a constant right hand side value. I will have a look.