[tliltocatl]

PC/x86 was an extreme outlier, sadly, and it was because of Microsoft/Intel business model. The architecture details was historically mostly decided on by Wintel, yet the system integration was done by many vendors, whose best interest was to stay as compatible as possible. Its unlikely that another platform would be able to reach this state, the PC architecturing was subsidized from the M$ software monopoly that nobody would have wanted to suffer thru again.

[ajxs]

> Its unlikely that another platform would be able to reach this state...

Is this really true? The computer ecosystem is more open now than ever. The original PC BIOS (which PC-compatible manufacturers needed to implement) was never an open, documented standard. It was a proprietary, closed system made by IBM. It's pretty fair to say that IBM didn't anticipate a PC/x86 ecosystem developing around their product. They even sued companies who made their own compatible BIOSes (like Corona). Intel didn't really have much to do with the success of the product at that point in time either, much less Microsoft.

In contrast, every widely-used modern system for hardware abstraction (UEFI/ACPI/DeviceTree/OpenSBI/etc) are open, royalty-free standards that anyone can use. Their implementation in ARM is newer, and inconsistent, but that's only because of how hugely diverse the ARM ecosystem is.

[LeFantome]

> Is this really true?

I think the issue is that desktop and server computing are “open” in the sense that you have full control over the software you run on them. So people interpret the dominant desktop and server platform architecture (the world of x86-64) as being open.

The embedded world is mostly closed, you are meant to run the software your hardware comes with. The platform’s popular there are considered less open (ARM and RISC-V).

Mobile devices like phones and tablets are historically closed devices, regardless of ISA. They are generally getting more closed in the name of security.

It is not the ISA that is “open” but the industry.

That said, in RISC-V, there is a sub-current of openness. I do not think that will overcome the industry tendencies in general, but there will be a small cadre of folks trying to create an open presence in every niche. The good news is that there is nothing to stop them. They will succeed eventually.

[tliltocatl]

The early PC era was a mess, and that's not the period I'm talking about. IBM was clearly not up to the task and Intel didn't care much yet, but Microsoft certainty did a lot for compatibility from the start (i. e. DOS abstracted away a lot of BIOS routines, so it would be easy to port MS-DOS to a non-IBM x86). But after IBM revealed MCA to show just exactly how much do they care about compatibility and platform openness, Intel realized they are missing out and cleaned up the MCA/EISA/VLB mess with PCI. Then Microsoft and Intel jointly released APM 1992 (which was clearly not enough), and then ACPI in 1996 (which is a total dumpster fire, but a sufficiently functional dumpster fire). I. e. ACPI and UEFI are exactly the product of the monopoly. M$/Intel profited from the abundance of cheapo white boxes, so it was in their best interest to come up with a standard even DELL can implement. The fact that AMD is going to implement the ACPI too wasn't much bother for Intel - they were so dominant that they could afford not to care.

On the other hand, ARM sells the cores to SoC vendors (and doesn't care much what becomes of it), SoC vendors ducktape the ARM cores to a bunch of Synopsys peripherals and sell the resulting SoCs to smartphone and car makers (and doesn't care much for the product). System integrators throw Android on top and sell it to the customers. Then Google, who get all the cream via Play, hides all the mess behind a thousand layers of Java abstractions.

DeviceTree is an offshot of Sun's OpenFirmware (and it leaves out all the hard stuff - OpenFirmware had Forth, DeviceTree expects the kernel to support every single brand of fan switch). OpenSBI is a disaster. I'm sorry, but what kind of bright mind came up with the idea of hiding damn *timer* behind a privilege switch? Timers were enough of a pain point on x86 already, then it settled on userspace-accesable RDTSC. RISC-V SBI? Reproducing x86 one stupid decision at a time.