Large data transfers are one of those things that always seem to find a way to be annoying. Tools like LocalSend make it easier over a local network, but wireless is not always an option, and some transfers are simply too important to leave to a Wi-Fi connection.In such a scenario, a wired solution that does not require setting up networking at all would be ideal.Intel's Thunderbolt maintainer Mika Westerberg and fellow Intel engineer Alan Borzeszkowski have been working on exactly that.USB4STREAM explainedThe two have put together a new protocol called USB4STREAM and a matching Linux driver called thunderbolt_stream. The approach is to let two or more machines transfer data directly over a USB4 or Thunderbolt cable without touching the networking stack at all.Once configured, each host gets a character device at /dev/tbstreamX that behaves like a regular file. Any application that supports read(2) and write(2) operations works with it without needing any special patches.In simple terms, any app that can perform read/write operations will be compatible with this.How it worksBefore data can flow, both machines need to have their streams configured. Streams are basically the individual data channels over the connection, and getting them set up is a matter of pointing both sides at each other through ConfigFS and assigning channel IDs.This can be done automatically or manually, depending on how much control you require.Once one side announces an active stream, the other can pick it up automatically just by using the same name for it. You can also run multiple streams at the same time, and the whole thing works alongside existing Thunderbolt plumbing without getting in the way.Closing a stream notifies the other end as well, so both sides know when the transfer is complete.When to expect?The patch is currently sitting in the Thunderbolt git tree's next branch. Assuming it gets submitted to the USB/Thunderbolt tree ahead of the Linux 7.2 merge window, it should land in that release. The ABI documentation in the patch already marks the target as v7.2.The driver ships as a loadable module named thunderbolt_stream and depends on USB4_CONFIGFS being enabled.USB4 keeps getting more relevantThe USB4 standard has been around since 2019 and has been getting steady attention in the kernel cycle after cycle. What was once an Intel exclusive, royalty-gated technology has gradually become the preferred high-speed port on modern motherboards across both AMD and Intel platforms, with Thunderbolt increasingly becoming a certification badge.USB4STREAM adds yet another practical reason to put that cable to work. If you have a USB4 port on your machine, then this driver could open up a surprisingly neat way to move data around without spinning up any networking at all.Via: Phoronix