Patch early, patch often, they say — almost 13 years early in the case of Debian’s patch for a potentially crippling issue with the way Unix-like systems represent time.
Debian 13 “Trixie,” scheduled for August 9, marks the Linux distribution’s mitigation of the Y2K38 bug, also known as the “Unix Epochalypse,” via a shift in the operating system to storing time in 64-bit variables for all but the oldest of supported hardware.
The Unix Epochalypse is the whimsical name for what could become a big problem if vendors and users don’t update their systems.
Like the Y2K bug before it, it’s an issue with the way software — in this case, Linux and Unix — handles dates.
The Y2K bug wasn’t so much a bug as a feature: an effort to conserve what was once scarce and expensive memory. Instead of recording all four digits of the year in a date, systems stored just the last two, assuming that ‘70’ referred to 1970. But as the millenium approached, that led to ambiguities: was ‘01/01/01’ a projection of a date in the near future, or a reference to an event almost a century in the past?
The consequences would have been disastrous had IT folks not burned the midnight oil fixing software and updating systems to store years as four digits and mitigate the ambiguities in data.
The Y2K38 bug presents a similar issue. Unix (and Linux) clocks count time in seconds, starting from January 1, 1970, which was dubbed the Unix Epoch, and some systems store that number in a signed 32-bit integer which will overflow at (brace yourself) precisely 03:14:07 UTC on January 19, 2038. When it does so, clocks will revert to December 1901.
Epochalypse now?
In fact, it’s already a real mess that is hitting systems, such as pension fund projections, that look into the future beyond that magic moment in 2038.
Said mess won’t affect modern 64-bit systems, of course — their dates are stored in 64-bit variables, good for more than 292 billion years. But legacy and embedded systems are at risk, hence the work by Debian and other distros. Everything from plant control systems and building monitoring systems to routers and security cameras are running some sort of embedded operating system, and for many, it’s 32-bit Linux. These systems often remain in service for decades without replacement, making a software fix a necessity. It’s another example how the failure to take hardware and software longevity into account can come back to bite us.
The cure: changing date storage to 64-bit variables. It was a massive task for Debian maintainers, involving almost 6,500 packages, and it all had to happen at one time because it also involved a change to the application binary interface (ABI). But Debian says the work is complete, or at least, as complete as it’s going to get for now. To ensure compatibility with x86 binaries, it is leaving dates on i386 systems as 32-bit, although it is considering options if there’s enough demand for 64-bit dates on those systems.
It may seem that the overflow is still a far-off problem but, “As of 2025, this is less that 13 years away, and plenty of systems that will have problems have already been shipped,” Debian said in a post about the issue. “We should stop adding to the problem. Most computing, especially computing using Debian or its derivatives, is now done on 64-bit hardware where this issue does not arise. However there is quite a lot of cost-sensitive 32-bit computing still out there, and still shipping in new devices (automotive, IoT, TVs, routers, plant control, building monitoring/control, cheap Android phones etc.), with some of that hardware probably running Debian or its derivatives.”
This is particularly important because many other Linux distros, including RedHat and Fedora, have already dropped 32-bit support, and SUSE’s support is unofficial, leaving the Debian ecosystem to carry a large part of the 32-bit load.
Most of the new 32-bit hardware still shipping will be running “build-from-source OSes like OpenEmbedded, or Alpine, Android, or Gentoo, but the Debian-based niche is likely to remain for some years, and some stuff built with it is likely to be in use/installed for long enough to reach Jan 2038,” the post pointed out.
A bridge to the future
This issue, like the Y2K situation before it, illustrates an industry-wide problem that should be addressed, noted John Annand, digital infrastructure practice lead at Info-Tech Research Group.
“The IoT and embedded operating system problems are symptoms of the fundamental differences between computer/software engineering and civil engineering,” he said. “Until regulatory bodies compel safety and longevity standards similar to what they have for bridges and buildings, software will always favour ease of innovation and speed of deployment.”
Source:: Network World