When I enable icmp, I see icmp in both ipv4 and ipv6 iptables:  
    0     0 ACCEPT     icmp     *      *       ::/0                 ::/0       
         ctstate NEW

But icmp in ipv6 is called icmpv6. So it all does not work and the traffic is
dropped:
> [285010.162912] IN_drop_DROP: IN=eth1 OUT= MAC=d8:9e:f3:f6:6d:0c:00:14:d1:e6:8d:c6:86:dd SRC=fe80:0000:0000:0000:0214:d1ff:fee6:8dc6 DST=2a01:4240:2e27:ad85:aaaa:0000:0000:070f LEN=72 TC=0 HOPLIMIT=255 FLOWLBL=0 PROTO=ICMPv6 TYPE=135 CODE=0 


And I see no way how to configure firewalld to add icmpv6 into ip6tables. I
have to use a direct rule:
firewall-cmd --permanent --direct --add-rule ipv6 filter INPUT 0 -p icmpv6 -j
ACCEPT

I would expect enabling icmp would enable icmpv6 in ip6tables, or at least
icmpv6 would be another option of protocol to be added.