I'm not using Petalinux: I just grabbed the BOOT.bin file from the starterkit, that's all.
IP address is statically defined in uboot (ipaddr env variable), as well as netmask and gateway ip.
When booting VxWorks kernel (from sdcard), it works: I can ping in both directions with same ipaddr, gateway, netmask than uboot
This means my laptop config is ok and the firewall is not blocking the connection
So my guess is that something must be wrong in the uboot config, but I can't figure out what it is.