At the Linux Foundation’s Open Source Summit, the Linux founder commented on the merging of Rust infrastructure into the Linux kernel. The plans are now more tangible.
The implementation of Rust for the Linux kernel seems to be taking shape soon: at the Linux Foundation’s Open Source Summit in Austin, Texas, Linus Torvalds announced that he expects Rust code to be merged into the Linux kernel in the near future. As a possible earliest date, he named the forthcoming release of Linux 5.20, which can be expected from the end of September if the previous release plans are adhered to (more on this in the last section of the message).
Rust as a second language next to Integrating C in the Linux kernel has been discussed for some time. In July 2020, Linus Torvalds publicly advocated the use of Rust code in the Linux kernel for the first time. At the beginning of December 2021, the Rust edition released in October brought decisive progress in the development of the programming language, and since then the integration project has relied on the stable Rust compiler as the infrastructure. The background to this is the expected greater stability and security, which would be guaranteed in particular by Rust’s standard memory security.
When Rust could move into the Linux kernel
Torvalds had on the Open Source Summit Dirk Hohndel, Cardano’s Chief Open Source Officer, announced in a public conversation that the patches required for the Rust merge had not yet been implemented because the Linux kernel maintainers were now much more cautious than they were 30 years ago years. For some in the community, the kernel maintainers would appear to be “too risk-averse”. “When it comes to Rust, it’s been discussed for several years, but we’ve gotten to the point now that we’re really going to put it in the kernel very soon,” Torvalds explained, adding, “Maybe in the next release.” (“Maybe next release.”)
According to those present, applause broke out at this point, which Torvalds immediately tried to dampen. Addressing the Rust fans in the audience, he emphasized the technical reasons such as memory security, for which he also thinks Rust is a good idea for the kernel. However, the merging is initially a trial run for him. He referred to the attempt 25 years ago to integrate C++. They tried it for two weeks and then let it go. “Rust is a way for me to try something new,” Torvalds continued, expressing his hope that it will work out this time (“hopefully, it works out”) since a lot of people have already put a lot of work into it.
Recalculated: time window for Linux kernel releases
As with previous release cadences, the “merge window” is open for two weeks after the mainline release, and new features can be added during this time be introduced into the kernel. This is followed by seven weeks for bug fixes and stabilization with weekly snapshots in the form of release candidates. Normally, this phase ends with the seventh release candidate (rc7), although other RCs are also occasionally present. The mainline releases follow each other roughly every nine to ten weeks.
The current version of the kernel is 5.18.7, which was released on June 25, 2022. The June 26 mainline release is at 5.19 on the fourth release candidate. A first mainline version of Linux 5.20 should therefore be available in about 10 weeks, purely mathematically. With the subsequent merge period, the merging of Rust code into the Linux kernel can therefore be expected in around three months at the earliest (end of September 2022). The Linux kernel archive provides information about the status of the releases, from where the current versions can also be downloaded.
A summary of the relevant statements by Linus Torvalds at the Open Source Summit can be read on Phoronix, the IT portal The Register was also represented by an employee on site and reported in more detail.