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OS/2 - ArcaOS 64Bits Kernel Discussion

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Martin Iturbide:

--- Quote from: Mentore on December 09, 2020, 08:14:08 am ---And yes, in my dreams I still think about a 64 bit recompiled OS/2 kernel :)

--- End quote ---

I would love to theorize about that in another forum thread. I know it is too hard, but it will be interesting to brainstorm with people with more knowledge on this subject. I will look on other past threads about this topic.

Regards

Joop:
As far as I know is that the memory is a little less than 4Gb. But this is for the whole OS, no matter if you have 1 kernel or 4 or 8 or... What could be done is each kernel its own little less than 4GB. So with a 4 kernel system you could install 16Gb memory. And 64-bit is a hoax. I have a W10 64-bit from work, everything is bigger including what you make with the applications, but no improvement on the 32-bit applications in my OS/2 system. We complain sometimes about this and that, with Windows 10 its worse. Each day I encounter problems with USB. The Wacom is sometimes working and sometimes not. Now this can easy be fixed, but its not okay. Office from Microsoft is a mess, really, no application does have the same file interface, parts are deaf for the cloud, some programs are even worse then found in the shareware corner. And you don't want to know what the company has to pay for this package.

Lars:
Physical addresses under OS/2 are also limited to 32-bit. Which means your approach of "4 GB of physical memory per core" cannot work.
You cannot address beyond the physical 4 GB boundary with the current OS/2. You would have to completely reimplement OS/2 memory management to support 64-bit physical addresses (and linear addresses).
Which becomes a massive problem because many new systems "waste" physical address space below the 4GB boundary by simply leaving it unused or by placing large regions of "non system-memory", for example, PCI address space.
And that's why there are machines that have 4 GB of system memory but can only use 2.5 GB or so under OS/2. That's because the other 1.5 GB of system memory are physically addressable beyond the 4 GB physical address boundary.

Jochen Schäfer:

--- Quote from: Joop on December 10, 2020, 10:17:08 pm ---And 64-bit is a hoax. I have a W10 64-bit from work, everything is bigger [..]

--- End quote ---
That's not a hoax, it is to be expected. If you want to address 64bit instead of 32bit, you need a bigger pointer. Most C/C++ compilers will make their types bigger, e.g. int going from 32bit to 64bit, so the data grows.  Everything grows, if you switch word size (32bit vs. 64bit). It was like that with the translation from 8bit to 16bit, then from 16bit to 32bit.
So, in a nutshell: Making your word size bigger, makes your executables and your data bigger. That's the downside for getting a so much bigger address space.

Jochen Schäfer:

--- Quote from: Lars on December 10, 2020, 11:22:46 pm ---Physical addresses under OS/2 are also limited to 32-bit. Which means your approach of "4 GB of physical memory per core" cannot work.

--- End quote ---
I remember, reading that the 64bit Darwin kernel always presents 32bit software with a 4 GB address space of its own. It does this via virtual addressing. This could be a way to go for OS/2, I think.

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