IoT Device Layout

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When modifying an IoT Core board support package (BSP), you can change the drive partitions and layout by modifying the DeviceLayout files.

Partition layout

IoT Core supports UEFI (GPT) and legacy BIOS (MBR) partition layouts. Most IoT Core devices use UEFI and GPT-style partitions, though Raspberry Pi 2 uses MBR-style partitions. To learn more about UEFI, read Boot and UEFI and the Windows and GPT FAQ.

Sample partition layouts included in the ADK Add-Ons:

  • \iot-adk-addonkit\Common\Packages\DeviceLayout.GPT4GB\devicelayout.xml
  • \iot-adk-addonkit\Common\Packages\DeviceLayout.GPT4GB-R\devicelayout.xml
  • \iot-adk-addonkit\Common\Packages\DeviceLayout.MBR4GB\devicelayout.xml
  • \iot-adk-addonkit\Common\Packages\DeviceLayout.MBR4GB-R\devicelayout.xml

These files use three component files:

  • DeviceLayout.<Name>.pkg.xml: Package file, creates packages for DeviceLayout and OEMDevicePlatform.xml.
  • DeviceLayout.xml: Specifies the device partition layout
  • OEMDevicePlatform.xml: Specifies the amount of free blocks available in the device and which partitions are compressed.

Partition layout (DeviceLayout.xml)

IoT Core requires 3 mandatory partitions (EFIESP, MainOS and Data). You can optionally include other partitions, for example, a CrashDump partition. Sizes are calculated in sectors, the default sector is 512 bytes.

Supported properties:

EFI: Fixed-size partition with the boot manager, boot configuration database. This partition is required for both MBR/GPT-style devices.

  • Name: EFIESP

  • Type: For MBR, use 0x0C. For GPT, use {c12a7328-f81f-11d2-ba4b-00a0c93ec93b}

  • FileSystem: FAT

  • TotalSectors: 65536 (= 32MB)

  • Bootable: true

  • RequiredToFlash: true

MainOS: OS and OEM-preloaded apps. This partition requires a minimum number of free sectors (MinFreeSectors) for normal operations.

  • Name: MainOS

  • Type: For MBR, use 0x07. For GPT, use {ebd0a0a2-b9e5-4433-87c0-68b6b72699c7}

  • FileSystem: NTFS

  • MinFreeSectors: 1048576 (= 512MB)

  • ByteAlignment: 0x800000

  • ClusterSize: 0x1000 (This size is recommended to keep the partition size manageable.)

Data: User data partition, user registry hives, apps, apps data. This partition is typically set to use the remainder of the storage space on the device. (UseAllSpace: True)

  • Name: Data

  • Type: For MBR, use 0x07. For GPT, use {ebd0a0a2-b9e5-4433-87c0-68b6b72699c7}

  • FileSystem: NTFS

  • UseAllSpace: true

  • ByteAlignment: 0x800000

  • ClusterSize: 0x4000 (This partition tends to be larger, so 0x4000 is recommended. 0x1000 is also OK.)

Crash dump partition: Optional partition, used to collect data from crash dumps. When used, size is given in total sectors.

  • Name: CrashDump

  • Type: For MBR, use 0x07. For GPT, use {ebd0a0a2-b9e5-4433-87c0-68b6b72699c7}

  • FileSystem: FAT32

  • TotalSectors: 1228800 (= 600 MB)

Required fields

These fields are required, the following values are supported for IoTCore:

  • Version: IoTUAP

  • SectorSize: 512

  • ChunkSize: 128

  • DefaultPartitionByteAlignment: 0x200000

Storage Size Estimations

The following diagrams provide an overview of two configurations.

2GB Configuration (2048MB, typically has 1843MB for storage)

2GB partition layout: EFIESP, MainOS, and Data. MainOS includes Windows and free space

Partition Contents MB Sectors Remarks
EFIESP EFIESP 32 65536 EFIESP size
Main OS Main OS 800 1638400 MainOS (estimate)
Main OS Free space 128 262144 MainOS Headroom
Data Data 883 1808384 Expands to fill free space
TOTAL 1843 3774464

4GB Configuration: (4096MB, typically has 3600MB available for storage)

4GB partition layout: EFIESP, MainOS, CrashDump, and Data. MainOS includes Windows and free space

Partition Contents MB Sectors Remarks
EFIESP EFIESP 32 65536 EFIESP size
Main OS Main OS 800 1638400 MainOS (estimate)
Main OS Free space 512 1048576 MainOS Headroom
CrashDump Crash Dump 600 1228800 CrashDump Size
Data Data 1656 3391488 Expands to fill free space
TOTAL 3600 7372800

Device platform layout (OEMDevicePlatform.xml)

OEMDevicePlatform.xml specifies the amount of free blocks available in the device and which partitions are compressed. Example:

   <?xml version="1.0" encoding="utf-8"?>
   <OEMDevicePlatform xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://schemas.microsoft.com/embedded/2004/10/ImageUpdate">
      <MinSectorCount>7372800</MinSectorCount>
      <DevicePlatformIDs>
        <ID>*</ID>
      </DevicePlatformIDs>
     <CompressedPartitions>
       <Name>MainOS</Name>
     </CompressedPartitions>
   </OEMDevicePlatform>