In 2018, Linux Is Still Receiving Fixes For The Apple PowerBook 100 Series
While Linux 4.17 is dropping support for eight obsolete CPU architectures, the kernel is still sticking around with obsolete hardware support. With the Motorola 68000 processors still being around, the Linux kernel "m68k" code continues to be maintained. But hitting the mailing list today were the m68k architecture updates and it included some updates for "Macintosh enhancements and fixes."
These Macintosh updates coming for Linux 4.17 include support for the real-time clock (RTC) on the PowerBook 100-series, PDMA support for the PowerBook 190, and some other code fixes/clean-ups for the Macintosh m68k code. Yes, really.
PDMA in this context is pseudo DMA support in the SCSI code. The PowerBook 190 series is from 1995 and at that time its Motorola processor is running at 33MHz and up to 8MB of memory. With the patch enabling PDMA support for the PowerBook 190, the sequential I/O read performance is said to improve by a factor of five.
Courtesy of Wikipedia, a look at the PowerBook 100:
Not sure what anyone would be doing with a PowerBook 100 series device on the latest Linux kernel code from 2018, but that's part of the 4.17 cycle and the possibilities with open-source. I'd hate to think how long it takes trying to compile any modern software on this device or even the length of the boot process...