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According Microsoft, "Universal Serial Bus Devices Do Not Work in Safe Mode" under XP. However, in my testing this is incorrect. USB keyboards, mice and flash drives seem to work fine in safe mode (I made sure the BIOS was not providing support). This makes sense because a failure of a standard input device would be, in Microsoft parlance, a "bad user experience".

So, Is USB supported in safe mode on XP?

  • If your answer is no (agreeing with Microsoft), please provide a test case, preferably in a virtual machine, where a standard HID keyboard or mouse fails. Please state hardware / BIOS / OS configuration. Note that you will need a PS/2 keyboard attached in addition to your USB device(s) in order to use the boot menu. Virtual machine software usually emulates a PS/2 keyboard. Alternatively, you could add the /safeboot switch to boot.ini.

  • If your answer is yes, please provide a link to some supporting documentation (either from Microsoft or someone authoritative).

Your answer might be "devices X, Y and Z are supported but nothing else", in which case also give a link.

Hugh Allen
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2 Answers2

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My answer is "yes" and I'm going to use the registry from a regular retail installation as my "supporting documentation", as I can't seem to find a link to a Microsoft article stating this officially.

For safe mode, Windows will load the drivers/device classes listed under the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal

On my test machine, I see device classes in there for USB controllers, human interface devices (KB / mouse), and disk drives. So, based on what I see there, I would expect a keyboard, mouse, and flash drive to work in safe mode.

Furthermore, I think you are misinterpreting the Microsoft KB article. I think the title refers to a specific problem scenario where the BIOS does not support USB, or the option is toggled off. The article is not stating that there is no USB support in safe mode.

BrianC
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Your USB devices work in Safe Mode because USB support is enabled in BIOS. If you go to "More Information" section in MS article, you will find the next statement "..In the case of USB input devices, in order for them to function in Safe mode, the system must have a BIOS with USB support for input devices and USB legacy mode must be enabled."

Thus, to make your USB devices to work in any mode, you need to enable USB support in BIOS. If this option is not available, try upgrading BIOS to a newer version.

Enable USB Support in BIOS explains how it can be enabled.

Volodymyr Molodets
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