Linus Torvalds believes ARM has little chance of usurping x86, because the latter has built an open hardware ecosystem that the former just doesn't look like replicating.
Torvalds voiced his opinions in a fireside chat with David Rusling, chief technology officer of ARM tools vendor Linaro, at the end of September.
Rusling asked Torvalds if he has a favourite architecture and Torvalds quickly responded that “x86 is still the one I favour most and that is because of the PC. The infrastructure is there there and it is open in a way no other architecture is.”
“The instruction set and the core of the CPU is not very important,” Torvalds added. “It is a factor people kind of fixate on but it does not matter in the end. What matters is the infrastructure around the instruction set. x86 has it and has it at a lot of levels.”
Torvalds said ARM's hardware story is strong in mobile, but that “I have been disappointed in ARM” because “as a hardware platform it is still not very pleasant to deal with."
“It does not have the same unified models around the instruction set as we do in the PC space, but it is getting better," he continued. "Being compatible just wasn't as big a deal in the ARM ecosystem as it was in the x86 system.”
In an ecosystem where compatibility is not the priority, Torvalds feels hardware vendors don't have an incentive to create the products that make a platform more useful.
The evidence, he said, is there to see in the fact that development for ARM nearly always takes place on an x86 PC. While Torvalds admires the Raspberry Pi, he classed it as a “toy” and said ARM cannot win until it provides a platform developers will want to use for their primary machines.
He's been trying to buy that PC for 30 years, he says, as his early experiences writing 6502 machine code gave him appreciation of the way ARM handles instruction pipelines. But the difficulty of getting an Acorn Archimedes machine to Finland saw him buy a Sinclair QL, an error that led him to understand the importance of platforms with wide support.
Torvalds said similar things about the internet of things (IoT). Asked about efforts to shrink Linux to run on very modest computing devices, he said the Linux development community won't make the effort to do so because “because most of the small devices tend to be very locked down.”
“I would like to say there are lots of IoT devices people will care about but when they are closed only people in companies care about them.” Which means the kernel won't include code to make them work well.
In any case, he feels that shrinking Linux may not be the way to advance the IoT, as even cheap hardware will get better. “People who want to fit things into 512k will find it hard to find chips with embedded SRAM because people will grow the hardware.”
Torvalds also touched on the vitality of Linux, saying that while it appears the operating system is evolving rather than adding new features big changes are being made to low level code without anyone particularly noticing. Asked if the age of the key contributors to Linux is an issue, Torvalds said he feels experience and continuity is valuable and that the number of contributors to Linux remains laudably high compared to engagement on other high-profile open source projects.
Rusling probed Torvalds on his behaviour and the Linux Lord said he feels misunderstood, as “99 per cent of the time I am a very happy manager and I mentally pat people on the head all the time.”
“I am an outspoken person and I used to say that on the internet nobody can hear you being subtle,” Torvalds said. Challenged that the language used on the Linux Kernel Mailing List is sometimes strong, Torvalds said terms like “hell no I will not every pull from you” are sometimes needed as “you cannot be nice and subtle all the time.”
“Sometimes my grumpiness makes more news than my being nice,” he said. “I feel like most of the time I am actually a very happy person.” He also pointed out that “we have had a wonderful dev process that really, really works.” ®