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Provisioning refers to the process of creating and defining LUNs on a new UFS device. A UFS device has one or more logical units. A logical unit is an independent processing entity within the device. Each logical unit has an address within the UFS device called a Logical Unit Number (LUN). The configuration file for provisioning is at <build root/common/config/ufs/provision. The provision XML files for the various UFS device versions are as follows:
  • provision_ufs22.xml - This is for UFS device 2.2 part
  • provision_ufs31.xml - This is for UFS device 3.1 part
In the UFS device provision XML file, the UFS Device Descriptor is a section that has essential information about the UFS device being provisioned. The Device Descriptor includes details such as number of LUNs, initial power modes, write boost parameters. Here is a sample device descriptor entry: 
<ufs bNumberLU="6" bBootEnable="1" bDescrAccessEn="0" bInitPowerMode="1" bHighPriorityLUN="0x5" bSecureRemovalType="0"
bInitActiveICCLevel="0" wPeriodicRTCUpdate="0" bConfigDescrLock="0" bWriteBoosterBufferPreserveUserSpaceEn="1" bWriteBoosterBufferType="1"
shared_wb_buffer_size_in_kb="4194304" />
The provision XML file also describes each LUN with Unit Descriptor parameters such as Logical Unit Enable, Boot LUN ID. The following is a sample LUN descriptor entry: 
<ufs LUNum="0" bLUEnable="1" bBootLunID="0" size_in_kb="4096" bDataReliability="0" bLUWriteProtect="0" bMemoryType="0"
bLogicalBlockSize="0x0c" bProvisioningType="2" wContextCapabilities="0" wb_buffer_size_in_kb="0"
desc="LU 0 - User LUN - Rest of the device" />
The following table describes some important parameters used in the provision XML files.
ParameterDescription
bNumberLUNumber of Logical Units. bNumberLU does not include well-known logical units.
bBootEnableIndicates whether the device is enabled for boot: 00h = Boot feature disabled, 01h = Bootable feature enabled
bDescrAccessEnIndicates whether the Device Descriptor can be read after the partial initialization phase of the boot sequence: 00h = Device Descriptor access disabled, 01h = Device Descriptor access enabled
BInitPowerModeDefines the Power Mode after device initialization or hardware reset: 00h = UFS-Sleep Mode, 01h = Active Mode
bHighPriorityLUNDefines the high-priority logical unit
bSecureRemovalType00h = Information removed by an erase of the physical memory; 01h = Information removed by overwriting the addressed locations with a single character followed by an erase; 02h = Information removed by overwriting the addressed locations with a character, its complement, then a random character; 03h = Information removed using a vendor-defined mechanism
bConfigDescrLock0h = Configuration Descriptor not locked; 1h = Configuration Descriptor locked
  • To reprovision the UFS device, set bConfigDescrLock="0". This parameter is part of the provision XML file.
  • To prevent reprovisioning, set bConfigDescrLock="1" after the UFS device configuration and provisioning is finalized.
ParameterDescription
LUNumLogical Unit Number
bLUEnableEnables/disables the logical unit: 00h = Disables the logical unit, 01h = Enables the logical unit
bBootLunIDBoot LUN ID: 00h = Not bootable, 01h = Boot LU A, 02h = Boot LU B
size_in_kbSpecifies LUN size in KBs
bLUWriteProtectLogical Unit Write Protect: 00h = LU is not write protected, 01h = LU write protected when fPowerOnWPEn = 1
bMemoryTypeDefines logical unit memory type: 00h = Normal memory, 01h = System code memory type, 02h = Non-Persistent memory type, 03h = Enhanced memory type 1, 04h = Enhanced memory type 2, 05h = Enhanced memory type 3, 06h = Enhanced memory type 4
bProvisioningTypeProvisioning type: 00h = Thin Provisioning is disabled, 02h = Enables thin provisioning with TPRZ = 0

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UFS device partition layout

The default UFS device provisioning creates eight LUNs (LUN0 to LUN7).
  • The Linux data and all Linux file system images are stored in LUN0.
  • Boot well-known LUN (WLUN) 0xB0 alternates between LUN1 and LUN2 to provide a fail-safe backup for the XBL.
  • The rest of the boot chain is stored in LUN4.
  • The LUN6 and LUN7 are unused by default.
Default UFS device layout