[blippage]

I was playing around with GPIO some time ago. The Linux kernel seems to adopt this approach. The first rule of Linux ABI is that thou shalt not break ABI.The second rule of Linux ABI is THOU SHALT NOT BREAK ABI.

So they had something like GPIOHANDLE_GET_LINE_VALUES_IOCTL, decided to change things around a little, so introduced GPIO_V2_LINE_GET_VALUES_IOCTL.

Although, as the saying goes, the problem with backwards compatibility is that anything that starts backwards stays backwards.

[blippage]

It also reminds me a little bit like DNA. There's a lot of cruft that doesn't do very much but the organism is still viable anyway.