What is max RAM installable?

[arcull]

Hi guys, I wonder how much ram can i put in my machine. I have free suse 10.2 (NOT the x64bit). Mother board supports up to 8GB. Will my suse recognize more than 4 GB? Thanks for help.

[elija]

If it is a 32 bit operating system it will only be able to address 4GB.

This is because the maximum a 32 bit unsigned integer can hold is 4,294,967,295. I
just did the maths on what a 64 bit integer can hold and it is 18,446,744,073,709,551,615.

I think 64 bit operating systems will be able to handle our memory requirements for a while

[khafa]

with a 32bit OS you can even make it support up to 64GB by recompiling the kernel and make it use high memory.

check this out
high memory

[elija]

Cool!

But mine is using 2gb by default - on another machine it is using 3gb
does this mean that that has already been done?

[khafa]

with 2 or 3 gb it can be that it was compiled for 4gb.

[gogalthorp]

With 32 bit and a vanilla kernel on a 4gig machine the max user space is 3 gig. ie the most any single process can address. The top gig is reserved for the OS.

With custom kernel compiles user space can be 4gig but with added overhead. ie it is slower. AFAIK this is still limited to a max user space of 4gig ie no single process will be able to address more then 4 gig no mater how much memory you have. Note it may be possible to have several processes each addressing 4 gig in memory at once (if you have the memory)

BTW this is exactly the same as in Windows (except there you don't have the option to recompile)

[arcull]

Thanks guys