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0 pointsdan-robertson1y ago0 comments

Historically this backwards compatibility was a competitive moat for intel – having a large supply of weird instructions with some undocumented behaviour thrown in makes it more expensive to make competing chips.

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loeg1y ago

The ISA isn't what makes x86 easier for operating systems to support than ARM SoCs. It's things like generic ACPICA instead of hardcoded devicetrees.

dan-robertsonOP1y ago

To be clear, I wasn’t claiming anything about operating systems. Merely that adding many weird instructions was a strategy intel used to try to make the jobs of amd and centaur and suchlike harder.

gjsman-10001y ago

Some ARM systems (mainly servers) do support ACPI; allowing for one image to run on multiple processors and devices.

However… ACPI is apparently a pretty awful thing to implement. When it doesn’t work, or mistakes are made (looking at my own 13th gen HP laptop right now - borked ACPI tables means unpatchable broken sleep on Linux), then it’s pure frustration.

Device trees on the other hand are much more binary. Either everything generally works or it doesn’t at all. It’s a valid approach.

10000truths1y ago

Flawed implementations of open specs can be worked around with things like quirk tables. A spec held hostage by a non-cooperating vendor cannot. In the world of ARM SoCs, bad vendors won't even provide a device tree, just a binary image compiled from a patched kernel.

AlotOfReading1y ago

You can override broken ACPI tables. The keyword to search for is "dsdt". For example, if you have an HP Omen this repo has a fix:

https://github.com/j0hnwang/OMEN-Transcend-16-ACPI-fix

But yes, device trees are far nicer to work with.

rldjbpin1y ago

nobody is a saint on this matter. both parties act the way they do to support their business position.

short-term support helps qualcomm sell more because their customers want to sell more phones to the same users. on the other hand, for the industrial partners there is an "LTS" model of support given (side effect being fairphone 5 https://news.ycombinator.com/item?id=37320800).

long-term support through backwards compatibility helps intel because they can sell new chips with the assurance that the ancient, unmaintained industrial software continues to run in a shinier box.

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