Linux will soon offer switchable x86-32 binary support

The merge window has opened for what will become Linux version 6.7, and below we've compiled some things that are likely to be included in the new release.

Now that really not very devilish kernel 6.6 is out, we can start to look forward to what will make up the next release, which will probably be finished some time early in 2024. The work-in-progress tree for things that might go into the kernel is collectively known as linux-next, and things that go into it may – but may not – make it into the next version. So what changes are happening already in linux-next form a decent indication of what lies ahead.

In a project of this ever-changing nature, driven by thousands of contributors, as new hardware support is added, support for old hardware is gradually phased out. Sometimes, that means types of hardware rather than specific devices, which can result in tens of thousands of lines of code being expunged as dozens of drivers collectively face the chop all at once.

Now that Intel's Itanium family of chips is fading into history, support for this unloved architecture in Linux is being dropped. The code was orphaned in early 2021, and although removal was vetoed in February, a patch to remove the code went through recently. In this context, IA64 denotes Itanic, not 64-bit x86, which is referred to as x86-64, AMD64, or X64 by different groups.

Another proposed change, currently at the "request for comments" stage, would remove drivers for a lot of early non-busmastering network cards, notably a dozen geriatric wireless cards. A little newer and a lot quicker, the driver for Qlogic's 10GbE QLGE card is going, too – but then Qlogic itself is gone, scoffed by Cavium who were in turn munched by Marvell.

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As we have described before, the developers behind the next-gen Bcachefs are trying once again, but this time its chances of inclusion look better: it made it into linux-next last month.

We suspect that quite a few distros would like to drop support for 32-bit x86 binaries, but a lot of people still use them. Ubuntu tried in 2019 but an outcry forced it to backtrack, so it just dropped support for 32-bit hardware. Users of 64-bit Ubuntu can still run 32-bit binaries today, and some of us do. This isn't just for gamers; for instance, The Reg FOSS desk still has WordPerfect 8 for Linux installed – released for free long before 64-bit PCs were even a daydream – and occasionally even uses it.

Part of the problem is that right now, 32-bit x86 support on 64-bit Linux comes in two separate parts: a set of 32-bit libraries that you can easily install, and inside the kernel itself, the 32-bit interfaces that those libraries need. Currently, if the kernel is compiled with those turned off, x86-32 code can't be executed. To make 32-bit support optional would be tricky; for example, vendors would have to supply two sets of kernels, one with 32-bit support and another without. So almost everyone just leaves it on.

A new patch will turn this into an option that the user can choose at boot time. That means that vendors could ship their distros with it turned off, but if the user installs 32-bit libraries, 32-bit binary support can be enabled; all that will be needed afterward is a reboot to run code built for older 386, 486, or Pentium chips.

There are a raft of other changes pending, including various improved Intel device drivers, some tweaks for handling AMD processors, and some improved Btrfs filesystem handling thanks to Valve's Steam Deck. For a more complete rundown, Linux benchmarking boffin Phoronix has a good overview. ®