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USB 3.0 debugger through a USB 2.0 port is not supported on Intel System-on-Chip (SoC) devices in Windows 8.1

This article describes an issue that occurs when you try to use the USB 3.0 debugger. We have released an update to resolve this issue. Before you apply the update, check out the Prerequisites for hardware settings in this article.
Consider the following scenario:
  • You have an Intel® Atom™ Processor Z373x series based or Intel Cherry Trail Cost Reduction (CHT-CR)-based computer that is running Windows 8.1.
  • The computer has an external USB 2.0 port.
  • You try to perform kernel debugging on the device by plugging a USB 3.0 cable into the USB 2.0 port.
In this scenario, the debug fails.
This issue occurs because Intel® Atom™ Processor Z373x and CHT-CR platforms do not provide xHCI debugging support because of pin reduction.
To resolve this issue, you can use one of the following methods.

Note After you apply this update, you can perform kernel debugging on Intel® Atom™ Processor Z373x and CHT-CR devices by plugging a USB 3.0 cable into the external USB 2.0 port. This feature is also supported on full Intel® Atom™ Processor Z374x, Z377x, Z378x, Z379x or N28xx/N29xx and CHT devices when plugging a USB 2.0 cable into the external USB 3.0 port, because the external USB 3.0 port is backward-compatible with USB 2.0.

Method 1: Windows Update

This update is available from Windows Update.

Method 2: Update Rollup

To resolve this issue, install the November 2014 update rollup for Windows RT 8.1, Windows 8.1, or Windows Server 2012 R2.

Prerequisites for hardware settings

To apply this update, you have to meet the following conditions:
  • The firmware should have the Extensible Device Controller Interface (xDCI) Debug Port Table 2 (DBG2) entry.
  • The xDCI controller is exposed correctly to the desired USB debug port.
  • The OEM firmware has to hide the xDCI controller in PCI, or expose it as an ACPI device instead of as a PCI device.

    Note The base address for xDCI will be pointed to by the DBG2 table entry.
  • The USB cable should be plugged in before the platform starts.

After you apply this update

The following scenarios are not supported:
  • There is no support for Power Management. This is the same as the Extensible Host Controller Interface (xHCI) debug solution currently available.
  • There is no support for hot-plug scenarios.
  • There is no support for USB-reconnection scenarios.
Additionally, after you apply this update, a polling mechanism is added to achieve and process events from the Event buffer. Because a polling mechanism is used, the rate of polling is faster than the rate of hardware events to fill the Event buffer.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
More information

File information

The global version of this update installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows 8.1 file information and notes

  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    VersionProductMilestoneService branch
    6.3.960 0.17 xxxWindows 8.1RTMGDR
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information" section. MUM, MANIFEST, and the associated security catalog (.cat) files, are very important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows 8.1
File nameFile versionFile sizeDateTimePlatform

For all supported x64-based versions of Windows 8.1
File nameFile versionFile sizeDateTimePlatform

Additional file information
Additional files for all supported x86-based versions of Windows 8.1
File propertyValue
File nameUpdate.mum
File versionNot applicable
File size1,788
Date (UTC)12-Oct-2014
Time (UTC)09:00
PlatformNot applicable
File nameX86_2ee78815f7cb476a9845d48a05dcfc0b_31bf3856ad364e35_6.3.9600.17399_none_c634bb3f034765ff.manifest
File versionNot applicable
File size727
Date (UTC)12-Oct-2014
Time (UTC)09:00
PlatformNot applicable
File nameX86_microsoft-windows-b..buggertransport-usb_31bf3856ad364e35_6.3.9600.17399_none_321788e02624b156.manifest
File versionNot applicable
File size2,437
Date (UTC)12-Oct-2014
Time (UTC)09:04
PlatformNot applicable

Additional files for all supported x64-based versions of Windows 8.1
File propertyValue
File nameAmd64_4741a62c88f843d3cbb9ca7c65c112d1_31bf3856ad364e35_6.3.9600.17399_none_426630d62bf83adb.manifest
File versionNot applicable
File size731
Date (UTC)12-Oct-2014
Time (UTC)09:00
PlatformNot applicable
File nameAmd64_microsoft-windows-b..buggertransport-usb_31bf3856ad364e35_6.3.9600.17399_none_8e362463de82228c.manifest
File versionNot applicable
File size2,441
Date (UTC)12-Oct-2014
Time (UTC)09:07
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size2,018
Date (UTC)12-Oct-2014
Time (UTC)09:00
PlatformNot applicable

See DBG2 spec to check for more information.

The following table contains the important fields for the xDCI DBG2 table entry:
Important FieldValue
AddressSpaceIDSystemMemory (0)
Register_Bit_Width32 bits (0x20)
BaseAddressRegister<Dynamically Assign based on xDCI PCI BAR0>
Port TypeUSB (0x8002)
Port SubtypeSynopsys xDCI (0x0007)
This update also contains two other important fixes that target the Intel SoC devices:
3002859 Miracast display resolution changes after you shut down and then start a Windows 8.1-based computer
3008242 The system does not enter Connected Standby after you install update 2996799 in Windows 8.1
See the terminology that Microsoft uses to describe software updates.
Third-party information disclaimer

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

Article ID: 3003727 - Last Review: 01/21/2015 05:35:00 - Revision: 4.0

Windows 8.1 Enterprise, Windows 8.1 Pro, Windows 8.1

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