Comment by p_l
1 year ago
The reality is that for highly integrated devices, you just ship a bunch of hacks, sometimes because you forgot to follow the spec and it was faster to patch a line in kernel than patch the firmware (Hello, intel mac broken ACPI tables!). A kernel driver for a phone component might have hardcoded set of quirks selected by string from device tree.
In the world of PCs, the reason Linux emulates Windows in terms of ACPI is because Microsoft not only is a big vendor - all those "designed for windows" labels on computers actually required passing test suites etc. Microsoft also publishes add-on specifications for things that are underspecced in ACPI - for example the ACPI spec does specify how to make an interface for backlight control. But it does not tell you the ranges that the OS and said interface have to support. Microsoft provides such description, that for example if OS responds with _OSI(Windows2003) then the supported ranges will be 0-5 (purely imagined example), but if it also responds _OSI(Windows2007) then the supported values can be 0-15, etc.
This is also why firmware situation on ARM is so shitty - vendors aren't forced to do the work, so they don't. With Windows, the vendor is external and it's pretty rare to avoid implementing things right (one example is Qualcomm fucking up Windows-on-ARM interfaces somewhat impressively and fixing it by injected drivers)
> The reality is that for highly integrated devices, you just ship a bunch of hacks,
That's true, but only in the specious sense that all integrated software is "a bunch of hacks". Fixing glitches due to misunderstandings between an API consumer and an API provider is something we all do, every day. And the essence of the problem is no different whether the technology is a Javascript app framework or a NVMe firmware driver.
I mean, sure, it's better to make sure that the NVMe firmware driver (picking on that because it was an example in the linked article) and the OS have a clean specification for interaction. And sometimes they do! But it's likewise important that everyone write appropriately idiomatic React code too, and we don't demand[1] a whole new technology idiom to prevent front end developers from doing dumb stuff.
The solution is about engineering practice and not technology, basically. ACPI isn't going to solve that, for the reason that ACPI didn't create the problem. It's not ACPI's problem to solve.
[1] Well, people kinda do, actually. Abstraction disease is another problem.