Linux kernel maintainer Greg Kroah-Hartman has responded to complaints that the current promise of two years for 5.10 is not enough, explaining that support is not automatic but requires commercial help.
Version 5.10 of the kernel was released in December and designated a "long-term maintenance" release, which generally means six years of support with important bugfixes and security patches. Broadcom's Scott Branden spotted that the official release table only specifies two years of support for 5.10, which has a projected EOL (end of Life) of December 2022. He raised a query on the kernel mailing list.
"The 5.10 LTS kernel being officially LTS supported for 2 years presents a problem," he said. "Why would anyone select a 5.10 kernel with 2 year LTS when 5.4 kernel has a 6 year LTS... a 2 year declaration is not LTS any more."
Maintainer Kroah-Hartman was quick to explain. First, he refuted the idea that two years is not LTS. "A 'normal' stable kernel is dropped after the next release happens, making their lifespan about 4 months long. 2 years is much longer than 4 months, so it still is a "long term supported" kernel," he said.
Second, he said that "every year we go through the same thing." The support is likely to be increased, he added, but only after companies pledge to back it. "I want to see companies using the kernel, and most importantly, updating their devices with it, to know if it is worth to keep around for longer than 2 years," he said. "I also, hopefully, want to see how those companies will help me out in the testing and maintenance of that kernel version in order to make supporting it for 6 years actually possible."
Kroah-Hartman challenged the thread starter to be among those companies. "When I get this kind of promises and support from companies, then I am glad to bump up the length of the kernel support from 2 to 6 years, and mark it on the web site. Traditionally this happens in Febuary/March once I hear from enough companies. Can I count on your support in this endeavor?"
He added that he does not recommend using a single kernel version for more than 2 years "on systems that you actively support and maintain". He blamed "customer-unfriendly SoC vendors" for providing "millions of [lines of] out-of-tree code" that is specific to that kernel.
A user replied that the device industry does not work at that pace. "Set-top-box and cable modem customers do want to use newer kernels but are so slow in adopting new ones that by the time they start the kernel has already been phased out 2 years ago," he said. "We have active customers... that use the 4.9, start adopting 5.4 now and by the end of this year the 5.10 kernel... These customers are a mix of RDK [Reference Design Kit] video, Android and just custom made Linux, they all want a 6 years LTS kernel though because it puts them on a support timeline they can work with given their pace and kernel expertise."
Kroah-Hartman observed that users can do their own LTS support, instancing Google's support of Android. "While Google is a great help to me in the LTS effort, providing huge amounts of resources... their promise to their customers/users does not depend on me keeping LTS kernels alive, if I stopped tomorrow their contracts are still in place and they know how to do this work themselves (as is proof with 3.18)," he said.
Will 5.10 get six years LTS? "So far the jury is still out for 5.10, are you willing to help with this? If not, why are you willing to hope that others are going to do your work for you? I am talking to some companies, but am not willing to commit to anything in public just yet, because no one has committed to me yet," Kroah-Hartman added. ®