TXCOMSTART/TXCMOTYPE of V5 SATA GTP with ISE10.1.1

1>is TXCOMSTART/TXCMOTYPE useful? My SATA controller includes OOB generate/detect circuit.During simulation,The V5 SATA GTP works well even if TXCOMSTART/TXCMOTYPE tied ground.I only input TILE0_TXDATA0_IN[15:0],TILE0_TXCHARISK0_IN[1:0] two tx signals .It can finish OOB negotiation with SATA device BFM.But,in real ML555 board, does it should be tied ground or connect logic?

2>TX buffer or TX phase alignment ?

Inside ISE10.1.1,the default SATA GTP configuration is TX buffer,no previous TX phase alignment.which better?

3>why not cominit sequence response from SATA DISK at ML555?

after sending COMRESET sequence, why not COMINIT sequence response from SATA DISK? Btw,the simulation result is ok.And that,i cann't detect any valid signal from tile0_rxlossofsync0_i[0].