The Qualcomm Emergency Download mode, commonly known as Qualcomm EDL mode and officially known as Qualcomm HS-USB QD-Loader 9008 [1] is a feature implemented in the boot ROM of a system on a chip by Qualcomm which can be used to recover bricked smartphones. [2] [3] On Google's Pixel 3, the feature was accidentally shown to users after the phone was bricked. [4]
For a device to support EDL it must be using Qualcomm hardware. The Snapdragon family is very widely used.
The Android Debug Bridge can be utilized to get access to EDL mode, with the command adb reboot edl. [2]
The Qualcomm Product Support Tool (QPST) is normally used internally by service center executives for low-level firmware flashing to revive Android devices from a hard-brick or to fix persistent software issues. To flash the firmware, the tool communicates with supported devices via EDL. [5] [ unreliable source? ] The QPST has not been officially released by Qualcomm.[ citation needed ]
Qualcomm Download (QDL) is a tool to communicate with Qualcomm System On a Chip bootroms to install or execute code. The source code is maintained by Bjorn Andersson aka andersson. [6] [ non-primary source needed ]
Qualcomm implemented motherboards always include a test point. These can vary between phone models. Generally, test points are a pair of contacts, which can be some way apart. EDL can be accessed by opening the back of the phone, finding the location of the test point, which depends on the model, and by using a pair of metal tweezers to short the connectors and boot the phone into EDL. Further software tools are needed for actions in EDL mode.
Qualcomm implemented motherboards, with the presence of EDL, can be booted to EDL via the use of a EDL Deep Flash Cable. This specific cable has a general appearance of a button present in the cable. The button can be represented as a switch, to be able to make the phone boot into EDL mode. With the use of the cable, in most devices and cases, it will not be necessary to use the test points. The cable also works on hard-bricked devices to boot them into EDL mode. This cable works by having a button present between D+ and GND.
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coreboot, formerly known as LinuxBIOS, is a software project aimed at replacing proprietary firmware found in most computers with a lightweight firmware designed to perform only the minimum number of tasks necessary to load and run a modern 32-bit or 64-bit operating system.
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Custom firmware, also known as aftermarket firmware, is an unofficial new or modified version of firmware created by third parties on devices such as video game consoles, mobile phones, and various embedded device types to provide new features or to unlock hidden functionality. In the video game console community, the term is often written as custom firmware or simply CFW, referring to an altered version of the original system software inside a video game console such as the PlayStation Portable, PlayStation 3, PlayStation Vita/PlayStation TV, PlayStation 4, Nintendo 3DS and Nintendo Switch. Installing custom firmware on some devices requires bootloader unlocking.
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Bootloader unlocking is the process of disabling the bootloader security that makes secure boot possible. It can make advanced customizations possible, such as installing a custom firmware. On smartphones this can be a custom Android distribution or another mobile operating system. Some bootloaders are not locked at all, others can be unlocked using a standard command, others need assistance from the manufacturer. Some do not include an unlocking method and can only be unlocked through a software exploit.
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