In article <[EMAIL PROTECTED]>,
Jeffrey Mark Siskind <[EMAIL PROTECTED]> writes:
> I have a question about __PAGE_OFFSET. I understand that the default setting
> is 0xC0000000 which means that physical memory is limited to 1G minus epsilon
> and that per-process address space is limited to 3G minus epsilon. And I have
> heard that you can change that to 2G minus epsilon physical memory and 2G
> minus epsilon per-process address space. I presume that the correct setting
> for that is 0x8000000. Is that true? I also have heard that physical memory
> plus per-process address space is limited to 4G. Is it trut that one could set
> __PAGE_OFFSET to any number? Could I set __PAGE_OFFSET to 0x4000000 and access
> 3G minus epsilon of physical memory while limiting per-process address space
> to 1G minus epsilon?
The kernel needs to map all user-space memory of a process into the virtual
memory map while it is running in that process context. If you have a a
process big enough that the mapping doesn't fit things will probably
break. It might work if you can guarantee that no single user process
ever grows bigger than 1G-epsilon, but that is not tested and a bit
fragile.
-Andi
