The talk is about the DM-Verity kernel device-mapper module for establishing root file system integrity and authenticity. It works by creating a hash tree and signing the root hash value for verification. It's a countermeasure against device manipulation during startup and runtime. Verification is performed on the fly with almost zero latency. The benefits include low overhead, termination of execution in case of manipulation, and the lack of need for secret keys. The talk also discusses the need for secure boot processes without gaps and the use of the device tree to specify different boot configurations. There is a brief Q&A section addressing on-the-fly verification and the placement of the kernel.