Three kernel developers describe what it's really like to work on the kernel, how they interact with developers from other companies, some pet peeves and how to get started. Like most Linux users, I rarely touch the actual code for the Linux kernel. Sure, I've looked at it. I've even compiled the kernel myself on a handful of occasions—sometimes to try out something new or simply to say I could do it ("Linux From Scratch" is a bit of a right of passage).

Some kernel developers recently have been trying to work around the massive, horrifying, long-term security holes that have recently been discovered in Intel hardware. In the course of doing so, there were some interesting comments about coding practices.

These days, Intel's name is Mud in various circles because of the Spectre/Meltdown CPU flaws and other similar hardware issues that seem to be emerging as well. But, there was a recent discussion between some Intel folks and the kernel folks that was not related to those things. Some thrust-and-parry still was going on between kernel person and company person, but it seemed more to do with trying to get past marketing speak, than at wrestling over what Intel is doing to fix its longstanding hardware flaws.

Dave Hansen from Intel posted a patch and said, "Intel is considering adding a new bit to the IA32_ARCH_CAPABILITIES MSR (Model-Specific Register) to tell when RSB (Return Stack Buffer) underflow might be happening. Feedback on this would be greatly appreciated before the specification is finalized." He explained that RSB:

Efforts to work around serious hardware flaws in Intel chips are ongoing. Nadav Amit posted a patch to improve compatibility mode with respect to Intel's Meltdown flaw. Compatibility mode is when the system emulates an older CPU in order to provide a runtime environment that supports an older piece of software that relies on the features of that CPU. The thing to be avoided is to emulate massive security holes created by hardware flaws in that older chip as well.

For weeks, the world's been talking about severe Intel design flaws affecting many CPUs and forcing operating systems to look for sometimes costly workarounds. Linux patches for these issues are in a state of ongoing development. Security is always the first priority, at the expense of any other feature. Next would probably be the general speed of a running system for the average user. After that, the developers might begin piecing together any features that had been pulled as part of the initial security fix.