Back around 1999 I tested some patches from Linux kernel hacker Jens Axboe that added packet writing support. This enabled DVD+RW discs to look like normal drives and you didn't have to make an ISO image and burn it.

https://www.kernel.org/doc/html/v6.1/cdrom/packet-writing.ht...

https://reactivated.net/software/packetwriting/

And in my googling for those links I find that Jens is still the block device maintainer and submitted a patch in 2025 to remove support for packet writing.

https://www.phoronix.com/news/Linux-To-Remove-pktcdvd

> "This driver has long outlived it's utility, and it's broken and unloved. The main use case for this was direct mount with UDF of cd-rw drives that required 32kb packets. It would collect writes into that size and write them out in multiples of that. That's not a common use case anymore, the world has moved on from those kinds of media. To make matters worse, it's actively breaking setups where it's not even required or useful."

There was a pretty short window where it was more useful than just dedicating 700mb of cache on the hard drive, about the time that CDs could easily be larger than your hard drive.