XPost: linux.debian.bugs.dist 
 From: csmate@nop.hu 
  
 hi, 
  
 On 10/21/25 15:02, Jason Xing wrote: 
 >> if you're in a need for some more complicated xsk tests, just let me know, 
 freertr 
 >> 
 >> have a dataplane and a socat-alike tool with an xsk based packetio for a 
 while.... 
 > 
 > Could you provide a link that points to what you just mentioned? I 
 > believe more tests on veth are necessary. 
 > 
  
 sure, but be warned, it's a huge rabbit-hole that you're jumping into.... :) 
  
 so the homepage is freertr.org, it provides a daily vm builds... 
  
 if you grab the qcow2, convert to raw and mount -o offset=1048576 
  
 you can update the kernel and initrd, and you need to put the xdp 
  
 bpf and elf libs as they're not part of that image... then umount it, 
  
 and after the first boot (look at the serial console!), do the following: 
  
 conf t 
 int eth1 
   vrf forwarding host 
   ipv4 addr 10.0.2.222 255.255.255.0 
   exit 
 ipv4 route host 0.0.0.0 0.0.0.0 10.0.2.2 
 end 
 write 
 test hwext path /rtr/rtr- dataplane p4xsk 
 reload cold 
 y 
  
 your xdp dataplath is activated, the vm kernel itself will be behind 
  
 a veth pair, the dataplane will play with the qemu virtio-pci and the veth, 
  
 and there will be an other veth for the dataplane-controlplane communication 
  
 full of random non-ip frames, then 
  
 ping 10.255.255.1 vrf host 
  
 ping 10.0.2.2 vrf host 
  
 will test for the fresh kernel and the outside word... 
  
 you can exercise the above with a raw socket on the original image if you do 
 "p4raw" 
  
 instead of "p4xsk", and as we're on the bpf, it have an in-kernel forwarder 
 called "p4xdp"....:) 
  
  
  
 the source is at https://github.com/mc36/freeRtr , the misc/native folder 
  
 contains the dataplane, and the socat-alike tools.... just ./c.sh to build 
 them... 
  
  
 afterwards you can create topologies with then like 
  
 (1.1.1.1/30)ns1-----------host-----------ns2(1.1.1.2/30) 
  
 to cross connect 2 interfaces on the host, just run 2 processes like 
  
 xskInt.bin veth1 skb 1234 127.0.0.1 4321 127.0.0.1 
  
 pcapInt.bin veth2 4321 127.0.0.1 1234 127.0.0.1 
  
 there are other tools with uring, raw socket, mmaped raw socket 
  
 and some others that are uninterested in the current topic imho.... 
  
  
 have a nice day, 
  
 csaba 
  
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