Rare project developers

[Alexander Gall <>]

Hi csaba

I'm adding support for the AS9516-32D to RARE but I'm hitting what I
believe is a compiler bug. It affects basically all profiles, for example

[~/rare]$ bf-p4c --std p4-16 --target tofino2 --arch t2na -Iprofiles/9.7.1 
-Ip4src -DCERN_FLOWLAB p4src/bf_router.p4
warning: ingress::ig_intr_md_for_tm.ucast_egress_port is read in ingress 
deparser, however it is never or partially initialized
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
bf_router.tofino2/pipe/bf_router.bfa:1909: error: No phv record 
ig_md.mpls_encap_decap_sap_type
failed command assembler

This happens for 9.7.1 as well as 9.9.0. I think it's a compiler bug
because the problem appears in the intermediate file bf_router.bfa. I
don't really understand that file, but I think the offending secition
is this:

   1893     p4_param_order: 
   1894       ig_md.srv_encap_l3vpn_valid: { type: exact, size: 1, full_size: 
1 }
   1895       ig_md.mpls_encap_rawip_valid: { type: exact, size: 1, 
full_size: 1 }
   1896       ig_md.mpls_encap_l3vpn_valid: { type: exact, size: 1, 
full_size: 1 }
   1897       ig_md.mpls_encap_l2vpn_valid: { type: exact, size: 1, 
full_size: 1 }
   1898       ig_md.mpls_encap_xconnect_valid: { type: exact, size: 1, 
full_size: 1 }
   1899       ig_md.srv_remove: { type: exact, size: 1, full_size: 1 }
   1900       ig_md.mpls0_remove: { type: exact, size: 1, full_size: 1}
   1901       ig_md.mpls1_remove: { type: exact, size: 1, full_size: 1}
   1902       ig_md.mpls_encap_decap_sap_type: { type: ternary, size: 4, 
full_size: 4 }
   1903       ig_md.nexthop_id: { type: ternary, size: 16, full_size: 16 }
   1904     row: 1
   1905     result_bus: 0
   1906     gateway:
   1907       name: ig_ctl_pkt_pre_emit_tbl_pkt_pre_emit-gateway
   1908       input_xbar:
   1909         exact group 0: { 0: ig_md.nexthop_id, 16: ig_md.srv_remove, 
25: ig_md.mpls_encap_decap_sap_type, 32: ig_md.mpls0_remove, 40: 
ig_md.mpls1_remove, 49: ig_md.srv_encap_l3vpn_val
   1909 id, 50: ig_md.mpls_encap_l3vpn_valid, 51: 
ig_md.mpls_encap_xconnect_valid, 57: ig_md.mpls_encap_rawip_valid, 58: 
ig_md.mpls_encap_l2vpn_valid }

The ternary key ig_md.mpls_encap_decap_sap_type appears in the "exact
group 0" list, which is probably wrong. At least this seems to be
confirmed by the BNG profile, which compiles fine with 9.7.1 but fails
with 9.9.0 and the difference is exactly that (the
mpls_encap_decap_sap_type does not appear in the "exact group 0" list
when the compilation succeeds).

If you can confirm this, we should open a case with Intel.

Unfortunately, there is an additional problem with 9.7.1 and the BNG
profile:

[~/rare]$ bf-p4c --std p4-16 --target tofino2 --arch t2na -Iprofiles/9.7.1 
-Ip4src -DPROFILE_BNG p4src/bf_router.p4
p4src/include/ig_ctl_vrf.p4(62): [--Wwarn=table-placement] warning: Shrinking 
table ig_ctl.ig_ctl_vrf.tbl_vrf: with 14 match bits, can only have 16384 
entries
    table tbl_vrf {
          ^^^^^^^
p4src/include/eg_ctl.p4(78): warning: egress::hdr.eth2.$valid is read in 
table tbl_eg_ctl78, however it is never or partially initialized
        if (hdr.eth2.isValid()) eg_md.pktlen = eg_md.pktlen + 14;
                                             ^
p4src/include/eg_ctl.p4(92): warning: egress::hdr.vlan2.$valid is read in 
table tbl_eg_ctl92, however it is never or partially initialized
        if (hdr.vlan2.isValid()) eg_md.pktlen = eg_md.pktlen + 4;
                                              ^
warning: ingress::ig_intr_md_for_tm.ucast_egress_port is read in ingress 
deparser, however it is never or partially initialized
Internal compiler error. Please submit a bug report with your code.

This bug also exists in 9.8.0 but not in 9.9.0 (in that case the BNG
profile also fails with the ig_md.mpls_encap_decap_sap_type error).

I fear that it will be difficult to convince Intel to back-port any
fixes to 9.7.x :( This looks like a show-stopper for us unless we give
up support for the APS2556...

-- 
Alex