On Sat, 7 Nov 1998, Jeffrey Mark Siskind wrote:
> 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
no, take a look at the description in include/asm-i386/page.h.
> 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?
'epsilon' has to be a power of two. (so it can be 3.5+512M, or 3G+1G or
2G+2G) Larry Auton has a nice patch that removes this constraint without
adding any cost.
-- mingo
