Zack's Kernel News

Zack's Kernel News

Article from Issue 206/2018

Chronicler Zack Brown reports on I3C support, fixing mmap(), and tracing RAM usage in OOM conditions.

I3C Support

Boris Brezillon posted some patches to implement a portion of the I3C core infrastructure. This is a wholesale upgrade of the I2C protocol for communications through serial ports. A lot of sensor devices use serial communications, because it's a simple two-wire interface. However, as that simplicity brings a proliferation of sensor devices, it becomes more important to manage the increased bandwidth and interrupt needs they create. I3C is designed to do that.

Boris' approach would transparently handle I2C backward compatibility for minimal user pain, but he also made certain compromises that would make using his APIs more difficult, and he left a fair chunk of the I3C API unimplemented for now, although he intends to fill it out in the future.

One implementation compromise was to require user code to run in a non-atomic context (i.e., only when the current process can be interrupted by something else). That's a slight annoyance, because it requires user code to be aware of its current state when calling the I3C API. However, Boris indicated he'd be fine with changing that. He'd mainly done it as a shortcut.


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