tom9876543 wrote:Korona wrote:Yes, the I/O APIC is a legacy device. On modern systems its only use is to route legacy PCI interrupts. Modern devices exclusively use MSI as that is demanded by the PCIe spec
OK I guess it depends on the definition of "legacy". I was thinking a standard PCI slot is not a "legacy" device, but maybe it is.
It's something of 'receding horizon' issue; eventually, most things in a field that is still changing rapidly become 'legacy' as newer hardware is developed, but at any given time 'current' is going to be a range of hardware from slightly different generations. I would say that standard PCI isn't quite legacy yet, but is just reaching that point, and for most newer hardware (less than, say, five years old) it is already there.
(Note that I said 'in a field that is still changing rapidly'. Even in the current world, many fields don't change much over a period of decades - housing, for example - and historically, most rates of change could be measured in centuries. Sooner or later - and I think it will be sooner than most expect - the rate of change in computer hardware and software is going to drop precipitously. Even now, it is far slower than it was in 1977, or even in 1997.)
So for a new OS, it is less a matter of what is and isn't legacy, as it is of how far back you want to support. For existing systems? They have support for older hardware already, so it becomes a matter of how long they have to continue supporting existing systems that have been or are being superseded, instead.
Pardon me for a moment while I get this soapbox out...
Most people working in the field don't really get that for most people who
aren't in the field - especially outside of the US, Western Europe, Australia, and the more industrialized Asian nations such as Japan, Taiwan, or South Korea (plus some of the more developed urban areas of mainland China) - having hardware that is over 5 years old is the norm rather than the exception. It is often even worse in the business world, and worse still in the public sector - I've been asked to maintain 10+ year old hardware more times than I care to remember by managers in both corporate and government offices, and in NPOs, twenty year old systems aren't unheard of even in the US.
In the US, most of the people who have new computers are ones who don't really care what they've got so long as they have the latest and greatest, whatever that is - and are likely to throw away the one they bought the year before, and replace it with an even newer one, rather than get someone to unclog their register and clean out the heavy loads of viruses and spyware they've accumulated in a year of careless use. But that's a minority of users; most have a smartphone from two or three generations back, and maybe a tablet and/or game console of the same vintage, but have never had a desktop or laptop PC of their own anyway (and wouldn't want one - they associate them with their jobs and classrooms, as something to escape from rather than bring into their homes).
Performance? Not really an issue - their hardware gets overwhelmed with malware faster than they could remove it, even if they knew how to or even really understood that it can be. To most people, having a new phone or tablet that runs at the same speed as their old one a week after they've turned it on for the first time is normal. The idea that something is wrong with a system when it gets like that just doesn't even occur to them. Why buy a new machine if it doesn't work any better than the one they have, especially since they can't afford it?
The point is, as enthusiasts, we don't really get that the average user wants something that is closer to a toaster, or at most a car, than to what most of us are looking for. They don't care how new it is, as long as it gets what they need done and they don't have to learn anything new to do it.
I'm not a fan of ACPI at all; I'm just trying to point out that it's always easy to cry about things that you don't have to design yourself.