In April, 2.4 kernel maintainer Willy Tarreau queried the Linux kernel mailing list regarding how the 2.4 kernel is still being used. He followed up summarizing the responses, suggesting that about 5% of 2.4 users run the kernel on old recycled laptops at home or on PDA's and thin clients, running whatever works with no real need to upgrade. Another 5% of the users are on desktop PCs and monitoring stations, not upgrading because "it works". From there, about 50% of the users run the 2.4 kernel on general purpose servers and update regularly, still running the older kernel due to lack of need for new features and lack of time, and possibly due to failed earlier attempts to upgrade. Another 20% use the 2.4 kernel on application specific servers where reliability is of the highest importance. 10% of the users run the older stable kernel on routers, firewalls, and intrusion detections systems, with 1 to 2 year uptimes and limited updates in a business setting, and shorter uptimes and frequent updates in a personal setting. The final 10% or so use the kernel in embedded systems where stability is again very important, and the build tree may be highly modified, causing at least one major network equipment manufacturer to still be shipping devices with the 2.4.2 kernel. Willy continued:
"Based on that and on the workflow people took the time to explain, I realize that the distinction between -pre and -rc is useless (ding! Linus if you read this, don't beat me). In fact, either people want absolute reliability and they pick one kernel from the stable 2.4.X.Y branch, or they want more recent updates and they simply do their shopping in the -master branch, which is fairly easy thanks to the Gitweb interface. But there are almost no testers in 2.4, just users. That means that I don't have to expect immediate feedback when posting a pre-release. And it has happened several times that I got a build error report several weeks after the release.
"Also, since most people do not update more than 1 - 2 times a year, it's not very useful to have more than 1 - 2 new versions a year, especially since we have the stable release. For this reason, I think I will issue stable releases a bit more often for users to quickly get their fixes, but progressively increase the delay between major releases. Those ones will only be issued with new PCI IDs, major driver updates, compiler support, etc..."