title: How BIOS decide to enable BME bit for PCI device during POST?
body: <p><strong>BME</strong> means "Bus Master Enable" and it is the Bit 2 in Command Register(offset 0x4) in PCI Config space. If this bit is set to 1 then this indicates the device has the ability to act as a <em>master</em> for data transfer. Besides, it is configured by system BIOS(as I knew...)</p>
  
  <p>My question is: how system BIOS decide this bit ? (based on class code or ...?)</p>