I meant that strictly in the realm of general-purpose operating systems (the article is, after all, about writing a Linux kernel). Two of those are DSPs. The Linux kernel and busybox account for 99,99% of the general-purpose code running on them, and bare-metal code for both is still very common. In fact, Linux runs on QDSP6 only under a hypervisor, and gained C6x support only somewhat recently (~5 years, I think?). Last time I saw a MIPS workstation was a very long time ago :-) and, barring a few niche efforts, the same goes for PowerPC as well.
Back when Linus was ranting, one could make a convincing case for supporting all of these architectures in an OS meant for general-purpose workloads, from server to desktop and from thin client (eh? feel old yet :-)?) to VCR -- and . Now you can sell an OS that supports nothing but x86-64 and a few ARMs, and you get most of the server market, and virtually all of the desktop and mobile market.
Obviously the architectures that you need for a particular project are the ones that you want to "care for" -- but in broad terms, it is perfectly possible today for someone to have worked as a programmers for ten years without encountering a single machine that is not either x86 or ARM-based. Someone who had 10 years of programming experience in 2003 probably ran into a SPARC system whether they wanted or not.
We are talking about Linux kernel here. There are billions of embedded processors running Linux on other than ARM and x86.
S390X (IBM mainframes) and OpenPOWER variants are fully supported by Ubuntu and those are not insignificant market either in banking, finance, or numeric computing.
One reason why Linux runs all Top 500 supercomputers is because it they have number of relatively recent systems close to the top running Sunway (Alpha derivative) , Power and SPARC64. Fastest supercomputer today runs on Sunway.
Name one recent android device using mips. There are, to my knowledge, only a handful of mips android devices (literally).
There was an announcement for a 64bit mips android device for 2016 (Warrior i6400) but I didn't hear anything about it. Did you?
Also there was an ainol tablet with the mips architecture (nov07) which flopped (those are the only instances I can recall where mips on android really came into play).
Back when Linus was ranting, one could make a convincing case for supporting all of these architectures in an OS meant for general-purpose workloads, from server to desktop and from thin client (eh? feel old yet :-)?) to VCR -- and . Now you can sell an OS that supports nothing but x86-64 and a few ARMs, and you get most of the server market, and virtually all of the desktop and mobile market.
Obviously the architectures that you need for a particular project are the ones that you want to "care for" -- but in broad terms, it is perfectly possible today for someone to have worked as a programmers for ten years without encountering a single machine that is not either x86 or ARM-based. Someone who had 10 years of programming experience in 2003 probably ran into a SPARC system whether they wanted or not.