What type of hardware support is required for getting the widevine L1 level? It s said that widevine L1 level requires hardware support so that it s impossible even for manufacturer to provide it through a system update.
But what exactly has to be done by the hardware?
Widevine digital rights management explained


To meet security Level 1, all content processing, cryptography, and control must be performed within the Trusted Execution Environment (TEE) of the device’s processor, to prevent external tampering and copying of the media file. All ARM Cortex-A processors implement TrustZone technology, creating a hardware separation that allows a trusted OS (such as Android) to create a TEE for DRM, and other secure applications.


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System update is at OS level (including drivers) but not at CPU/ TEE level which are totally independent. Quoting from wiki

The TEE is a standard which creates an isolated environment that runs in parallel with the operating system, providing security for the rich environment. It is intended to be more secure than the User-facing OS. ARM TrustZone TEE is an implementation of the TEE standard

For more , see The Complete Guide to Widevine
Google’s DRM Platform