Boot - Qualcomm Dragonwing Documentation

XBL

The boot devicetree properties explain how to enable and disable user-initiated emergency download (EDL) in XBL. You can use the detailed EDL timeout and the USB cable options that can force the system into EDL mode. You can use these properties to configure boot-related functionality. The boot DT file path on the Linux build computer is /boot_images/boot/Settings/Soc/<chipset>/Core/Boot/sw_boot.dtsi.

Table: Boot DT properties

Property name	Property description	Data type	Possible values / value range	Device behavior
`vibration`	Turn on or off vibration at XBL exit.	UINT32	• `0x00` • `0x01`	• ENABLE (0x01): Turns on the vibration. `0x01` is the default setting. • DISABLE (0x00): Turns off the vibration.
`forced_download.feature`	Enable or disable the forced emergency download mode (EDL) feature at the XBL stage. Flash images using a USB cable along with key combination (Press POWER (PWR), VOL+, and VOL‑ keys together).	UINT32	`0x00`	Force EDL feature (FEDL) DISABLE (0x00): FEDL is disabled.
`forced_download.feature`	Enable or disable the forced emergency download mode (EDL) feature at the XBL stage. Flash images using a USB cable along with key combination (Press POWER (PWR), VOL+, and VOL‑ keys together).	UINT32	`0x01`	ENABLE (0x01): Enable user‑initiated EDL in XBL.
`forced_download.check_usb_option`	To enter FEDL mode, select the USB cable options.	UINT32	`0x00`	CHECK_USB_D_PLUS_GROUND (0x00): Device enters EDL mode when powered on using a special USB cable that grounds the D+ line. This is the default setting.
`forced_download.check_usb_option`	To enter FEDL mode, select the USB cable options.	UINT32	`0x01`	CHECK_USB_D_PLUS_HIGH_WITH_TIMEOUT (0x01): Connect the device to USB + ground during boot. Device is forced into EDL mode if the connection is removed within the boot timeout.
`forced_download.check_usb_option`	To enter FEDL mode, select the USB cable options.	UINT32	`0x02`	• Timeout is provided by the `forced_download.check_dp_timeout` DT property in milliseconds (ms). • CHECK_USB_REGULAR_CABLE (0x02): Device is forced to EDL when booting with a normal USB cable.

UEFI

In the UEFI environment, the device path protocol defines how to connect and identify the devices, with nodes being part of this protocol. The UEFI file path on the Linux build computer is /boot_images/boot/Settings/Soc/Core/Uefi/cfg/ueficfg.dtsi. The following table lists the main types of UEFI device path nodes and property names.

Table: UEFI device path nodes and properties

Property name	Property description	Data type	Possible values / value range	Device behavior
`OsConfigTableSelection`	Selects the hypervisor to be booted. The values are as follows: 0x1 - BOOT_TYPE_LINUX - Gunyah ^TM Hypervisor Software 0x2 - BOOT_TYPE_LINUX_WITH_KVM	UINT32	Range is from 0x1 to 0x2 depending on the hypervisor.	Hypervisor is chosen based on the selected value.
`QcCapsuleRootCert`	Root certificate for capsule authentication. This node has the entire root certificate content.	UINT8 list	Has the OpenSSL generated certificate content.	Certificate used in Capsule authentication
`BootFromNvme`	Enables Boot from NVMe media.	UINT32	0x1 indicates Boot from NVMe media enabled	When set to 0x1, EDK II will enumerate the NVMe media and boot Linux from the same, if present

These UEFI DT properties, including OsConfigTableSelection, are also used to select the default hypervisor (Gunyah or KVM) for a platform. The binary file that carries these UEFI DT nodes—xbl_config.elf/xbl_config_kvm.elf or uefi_dtbs.elf/uefi_dtbs_kvm.elf—depends on the platform. For the full platform breakdown, see Boot interfaces overview.

​XBL

​UEFI

XBL

UEFI