On Thu, Apr 8, 2010 at 1:29 PM, Joel Fernandes <[email protected]> wrote:
> Hi Venkatram, > thanks for your wonderful explanation, I delayed asking further questions > till I read every ones posts, its much clearer now. :) > > To make things clear, 896 MB is not a hardware limitation. The 3GB:1GB >> split can be configured during the kernel build but the split cannot be >> changed dynamically. >> > > Actually someone further along in this thread mentioned that the value of > LOWMEM / HIGHMEM can be a hardware constraint such as in the case of x86 > it is a hardware constraint in other architectures like MIPS, not x86. > > >> Hope this clears the confusion. >> > > Surely does, thank you. I have one more question, the memory between 896MB > and 1GB (128 MB) is actually the kernel virtual memory that is dynamically > mapped to highmem using kmap or used for vmalloc/IO right? and the 896 MB of > physically memory which is directly accessible is what contains the actual > page tables that make accessing high mem using the 128MB kernel virtual > address space possible right? > Correct > > You said page tables are stored in the 128 MB portion, I'm confused because > the 128 MB is virtual and the page tables have to be stored in the 896 MB > segment. no? > I was wrong, page tables are stored in the kernel data area as told by Chetan Nanda. > > -Joel > >
