A bit of history on how DMA (Direct Memory Access) works. Despite being 6 years old, it worth the lecture: An overview of direct memory access
What is open-source hardware? If you had the same question, you might be interested in this article: Open source hardware risks. Also, the article brought to my attention the following projects: OpenTitan, Root of Trust in cryptography, Chiplet technology, IBEX RISC-V core, Ariane Risc-V CPU.
In contrast to the above article on Open Source Hardware, a colleague of mine indicated an article by Paul McLellan (Cadence) describing a different view on the open-source paradigm: Open source in 2020. Paul reveals a webpage which seems to be the first in line when it comes to critique on open source concept. It is called The Cathedral and the Bizarre, a parody name in response to the book The Cathedral and the Bazaar written by Eric S. Raymond in 1998, who laid the foundation for open source movement.