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A comment on Intel mulls cutting 16 and 32-bit support, booting straight into 64-bit mode. Parent comment

Re:Intel mulls cutting 16 and 32-bit support, booting straig... by jeffbee on Thursday May 25, 2023 @02:28PM (#36074255)
Yeah but who, other than the person responsible for the firmware that boots the system, cares? These simplifications will have zero observable benefits to you. They won’t save a lot of die space or cost.

The complexity of the far past is so small that it is inconsequential today. The PS1 was implemented in spare die area of the PS2’s USB controller. Time marches on and die space becomes free.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by jkingsman on Thursday May 25, 2023 @02:34PM (#36074357)
> The PS1 was implemented in spare die area of the PS2’s USB controller

Whoah, that is WILD. Any info about where I can learn more about this?

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by nateguchi on Thursday May 25, 2023 @02:48PM (#36074496)
https://www.copetti.org/writings/consoles/playstation-2/

Under heading “I/O”

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by tobz1000 on Thursday May 25, 2023 @02:50PM (#36074527)
It sounds more like the I/O firmware was running on dedicated PS1 hardware:

https://www.theguardian.com/technology/2013/dec/12/ps4-and-x...

> The PlayStation 2, meanwhile, had the original PlayStation chipset built in, so it ran pretty much any PSone title – and when that chip wasn't being used for backwards compatibility it doubled as an input/output processor, which was pretty canny.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by mikeponders on Thursday May 25, 2023 @02:55PM (#36074578)
https://www.copetti.org/writings/consoles/playstation-2/#io

Essentially the thicc PS2s include the PS1 chip and normally use it for IO and also for PS1 compatibility.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by kibwen on Thursday May 25, 2023 @02:34PM (#36074352)
True that it's invisible to end-users, but it's still a pain in the ass to people writing OSes. Lowering the barrier to entry even a little bit will be appreciated by hobbyists.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by t0b1 on Thursday May 25, 2023 @02:43PM (#36074436)
How so? The bootloader already runs in long mode with UEFI and it also takes care of bringing up other cores so this is not really a problem in my experience.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by monocasa on Thursday May 25, 2023 @03:20PM (#36074900)
UEFI doesn't really take care of bringing up the other cores. There's a way to get access to them, but you have to give them back to UEFI before exiting boot services, so that doesn't really help your kernel. You still need to do the SIPI into x86-16 code to really take control of the AP cores.

Even the new way (that isn't actually implemented AFAIK) just SIPIs into long mode code, it doesn't use the UEFI multicore stuff.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by JoshTriplett on Thursday May 25, 2023 @03:18PM (#36074868)
Linux still needs to use a Startup IPI to bring up other CPUs, which starts them running in 16-bit mode at an address under 1MB.

Having a fully 64-bit way to bring up other CPUs would simplify that.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by DSMan195276 on Thursday May 25, 2023 @03:34PM (#36075076)
From a hobbies point of view I'd actually argue the opposite. The nice thing about the old stuff (Ex. the 8259 PIC support they're removing here) is that it's much simpler to get going. They have very large limitations, but those don't matter when just starting, and they serve as a good stepping stone and learning opportunity before eventually moving on to the modern and more complicated stuff. Additionally if you're using a bootloader then the bulk of this is already solved for you anyway.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by rbanffy on Thursday May 25, 2023 @04:30PM (#36075777)
The modern stuff is only more complicated because it had to be built around and on top of dozens of dead civilisations under it.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by hulitu on Friday May 26, 2023 @04:10AM (#36081417)
This is the simplistic explanation.

I think that besides that, some people are paid for complexity. That would justify the evolution of SW in the last 10 years.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by meepmorp on Thursday May 25, 2023 @02:47PM (#36074482)
> The PS1 was implemented in spare die area of the PS2’s USB controller.

This really confused me until figured out you weren't talking about the IBM PS/1 and PS/2.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by Narishma on Thursday May 25, 2023 @03:03PM (#36074678)
I don't think they are. IBM PS/2 was more than a decade before USB.

But then, the PS2 console didn't have USB either, so I'm not sure what they're talking about.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by circuit10 on Thursday May 25, 2023 @03:12PM (#36074786)
> The PlayStation 2 also features two USB ports

https://en.wikipedia.org/wiki/PlayStation_2

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by GenerWork on Thursday May 25, 2023 @03:13PM (#36074797)
PS2 had 2 USB ports on the front, did it not?
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by ace2358 on Thursday May 25, 2023 @03:30PM (#36075021)
Yeh and the original had a FireWire port too!
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by Narishma on Thursday May 25, 2023 @07:15PM (#36077670)
You're right. I guess I never noticed because they didn't use it for the controllers.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by shpx on Thursday May 25, 2023 @02:52PM (#36074553)
I care. I want to learn the entire thing I'm using, which means I appreciate things that are simpler and faster to learn. You can say I am a stupid or irrational person not worthy of consideration for wanting this but I am who I am and I want to spend money on computers that cater to me.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by tedunangst on Thursday May 25, 2023 @04:42PM (#36075935)
Do you want a computer architecture that replaces and obsoletes everything you've previously learned or one that evolves and adds new features on top?
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by solarmist on Thursday May 25, 2023 @07:21PM (#36077723)
Either depending on the situation.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by bdamm on Thursday May 25, 2023 @04:49PM (#36076023)
Then you are obviously running OpenBSD on ARM.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by jacquesm on Thursday May 25, 2023 @05:21PM (#36076386)
In that case you should probably not look at x86 at all. It's one of the most convoluted architectures out there, especially because it lugs all of that legacy stuff along.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by phendrenad2 on Thursday May 25, 2023 @05:26PM (#36076457)
When people say "who cares?" they generally mean "what non-vanishingly-small percentage of people care?" and I think that's still an unanswered question!
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by citrin_ru on Thursday May 25, 2023 @06:01PM (#36076861)
It very similar to chip die space - modern technologies are so complex that to learn how 8086 works is a very small effort compare to learning how the latest intel CPUs work. And emulation of older generations is a small part of this complexity.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by nneonneo on Thursday May 25, 2023 @07:14PM (#36077658)
I'd argue that 16-bit mode is conceptually more complicated than modern 64-bit modes, at least for userspace. 64-bit mode has a single flat address space (FS/GS are just opaque offsets into this address space), memory-mapped I/O, and a single system call trap instruction. 16-bit mode has segmentation, I/O ports, multiple trap instructions (and call gates!), address space wraparound...
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by shpx on Friday May 26, 2023 @03:01AM (#36080949)
Learning useful things is fun, learning useless things is unpleasant, so in some sense it's more effort.
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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by citrin_ru on Friday May 26, 2023 @03:38AM (#36081210)
While working on not always pleasant stuff at paid job as a hobby I sometimes learn 'useless' stuff from the past. For me on average old technologies looks simpler (though not without quirks) and more interesting to learn while modern ones often look over-complicated.

Just to clarify - I don't think that Intel should retain 16bit mode, but don't think removing it would make a big difference.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by amluto on Thursday May 25, 2023 @03:47PM (#36075226)
The OS cares, sadly. When the OS, running one one CPU, instructs another CPU to start (which happens — your system boots into your OS and also resumes from suspend with only one CPU running OS code), it sends a message called SIPI to that CPU. The CPU responds by running OS code, in real mode, at an address <1MB. So the OS needs to find valid memory below 640kB that doesn’t conflict with any other horrible legacy use.

Also, the “LA57” 5-level page table design has a little whoopsie: you can’t switch between 4 and 5 level page tables without exiting paged mode entirely.

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Re:Intel mulls cutting 16 and 32-bit support, booting straig... by q1w2 on Friday May 26, 2023 @09:24AM (#36083767)
While all true, obviating all this has no material impact on the user.
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