Re: 32-bit memory limits IN DETAIL (Was: perspectives on 32 bit vs 64 bit)

[Martin Kuball <martinkuball@web.de>]

Am Tuesday, 25. October 2005 02:31 schrieb linux@horizon.com:
[snip]
> Because the kernel address space has to hold more than just RAM (in
> particular, it also has to hold memory-mapped PCI devices like
> video cards), if you have 1G of physical memory, the kernel will by
> default only use 896M of it, leaving 128M of kernel address space
> for PCI devices.
>
> A different user/kernel split can help there.  I use 2.75/1.25G on
> 1G RAM machines, but if you use PAE or NX, the split has to be on a
> 1G boundary.
>
>
> But these are all workarounds.  The real solution is to use a
> larger virtual address space so that the original, efficient
> technique of mapping both the user's virtual address space and the
> kernel's address space (basically a copy of physical memory) will
> both fit.

And what about 64bit systems? How is the splitting done there? Do I 
have to worry?

Martin