how to activate the TCP Fast Open in linux

I have 2 PCs linux (PC1: kernel 3.13.0-37 and PC2: kernel 3.11.0-12)

PC1-------PC2(TCP server port 4410)

From PC1, I m sending a tcp packet with TCP Fast Open (Fast Open Cookie Request)

I m expecting to get an answer from the server with TCP option (Fast Open Cookie: xxxxxxx) something like this:

But I got a tcp packet without the TCP option (Fast Open Cookie: xxxxxxx).

I m wondering if there is something to configure on my PC2 (linux) in order to activate the TCP Fastt Open option.

For the TCP server, I m running a php script:

$sock = socket_create(AF_INET, SOCK_STREAM, 0);

// Bind the socket to an address/port
socket_bind($sock, "0.0.0.0", 4410) or die('Could not bind to address');
for(;;) {
    // Start listening for connections
    socket_listen($sock);
    ...
}

You have to enable TFO in the server's listening socket with:

int qlen = 5;
setsockopt(fd, SOL_TCP, TCP_FASTOPEN, &qlen, sizeof(qlen));

(https://lwn.net/Articles/508865/)