Electronic device having efficient power supply capability

1. An electronic device comprising:

a first switch which switches between connection and disconnection of a signal line for receiving a sideband signal transmitted from a device attached to the electronic device;

a second switch which switches supply and interrupt of power to the device independently from other components in the electronic device;

a nonvolatile memory which holds a setting, the setting indicating whether the device is to be enabled or disabled; and

a control section which controls the first switch and the second switch based on the setting at power-on of the electronic device, wherein, when the setting indicates that the device is to be disabled, the control section causes the second switch to interrupt power to the device.

2. The electronic device according to claim 1 , wherein when the setting indicates that the device is to be disabled, the control section causes the first switch to disconnect the signal line for receiving the sideband signal transmitted from the device.

3. The electronic device according to claim 1 , wherein the setting is a setting of a basic input/output system.

4. The electronic device according to claim 1 , wherein the device is attached to the electronic device in conformance with PCI Express standards and the first switch disconnects the sideband signal in conformance with PCI Express standards.

5. The electronic device according to claim 1 , further comprising:

a logic circuit which switches between permitting and inhibiting transmission of a reset signal to the device, wherein the control section causes the logic circuit to inhibit transmission of the reset signal to the device when the setting indicates that the connected device is disabled.

6. A method for powering on an electronic device that includes a connected device, the method comprising:

providing, by a switch, connection and disconnection of a signal line for receiving a sideband signal transmitted to the electronic device;

supplying power to the electronic device by a power switch;

reading a setting held in nonvolatile memory responsive to the supplying power, the

setting indicating whether the connected device is enabled or disabled; and

controlling the switch and the power switch based on the setting, the controlling includes interrupting, by the power switch, a power supply exclusively to the connected device when the setting indicates that the connected device is disabled while other devices within the electronic device are continued to be supplied power.

7. The power supply method according to claim 6 , wherein the setting is a setting of a basic input/output system.

8. The power supply method according to claim 6 , further comprising disconnecting a sideband signal transmitted from the connected device to the electronic device when the setting indicates that the connected device is disabled.

9. The power supply method according to claim 8 , wherein the connected device is a PCI Express device and the disconnecting the sideband signal is performed based on PCI Express standards.