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by vardump 523 days ago
32-bit ARM-based systems supported up to 1 TB of RAM. 32-bit x86 only up to 64 GB. Unless you want to map more than 4 GB in a single process, you could very well stay 32-bit.

But AArch64 (or ARM64) and AMD64 did bring a lot more on the table than just larger address space. More registers, and a performance boost by just being better suited for the modern CPU core design.
4 comments
ploxiln 523 days ago
32-bit x86 linux will typically support 3GB per process, with 1GB kernel address area, I think? (Windows did 2GB / 2GB split by default, custom boot options can change it to 3GB / 1GB, but only some 32-bit apps fully supported it, like photoshop).

Also, FWIW, security people can get real bothered that ASLR doesn't do much in 32-bit systems.

So, I think starting around 2GB DRAM, it's probably a "big enough" system to justify a 64-bit OS.

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junon 523 days ago
On 32 bit you can of course make the kernel higher half, but yes AFAIK most mainstream kernels chose higher quarter to grant more vaddr space to processes.
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garaetjjte 523 days ago
>Unless you want to map more than 4 GB in a single process, you could very well stay 32-bit.

Provided you are not bothered by highmem. https://www.realworldtech.com/forum/?threadid=76912&curposti...

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lproven 523 days ago
I didn't notice who wrote that initially, and was getting annoyed with his failure to notice that it's not HIGHMEM.SYS, it's HIMEM.SYS.

But why should Linus, even in 2007, use Win9x in the 21st century?

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bpye 523 days ago
> But AArch64 (or ARM64) and AMD64 did bring a lot more on the table than just larger address space. More registers, and a performance boost by just being better suited for the modern CPU core design.

There is the x32 ABI - 32-bit pointer length, but the AMD64 ISA. I don’t think it ever saw significant adoption though.

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junon 523 days ago
32 bit gave you that much with PAE, which has its own set of unfortunate problems.

I still think it's pretty safe to say 64 bit is the future, and will be for a long time (if I live long enough for 128 bit processors to become defacto or even widely necessary I'll be truly shocked).

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