On 02/07/2019 21:12, druck wrote:
> On 02/07/2019 09:10, The Natural Philosopher wrote:
>> Umm. Can a 32 bit OS run 64 bit programs?
>
> No that isn't possible as a 32 bit OS can't set up the required 64 bit
> configuration. But a 64 bit OS can run both 64 bit and 32 bit programs.
>

That is what I thought.

So unless you are coding in assembler,  your system calls will dictate
using a 32 bit instruction set.



> There is also a mode called ILP32, which uses the 64 bit ARMv8
> instruction set, but 32 bit longs and pointers. So you get the benefits
> of the improved instruction set (more registers, better branch
> prediction), but avoid the disadvantage of increased cache when dealing
> with 64 bit values.
>
> The only drawback is you need a complete set of ILP32 compiled userland
> libraries, nearly doubling the size of your OS image (or adding another
> 50% if you've already got a true 32 bit userland).
>
Very interesting.


> ---druck


--
If you tell a lie big enough and keep repeating it, people will
eventually come to believe it. The lie can be maintained only for such
time as the State can shield the people from the political, economic
and/or military consequences of the lie. It thus becomes vitally
important for the State to use all of its powers to repress dissent, for
the truth is the mortal enemy of the lie, and thus by extension, the
truth is the greatest enemy of the State.

Joseph Goebbels

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