Messages in this thread |  | | Date | Thu, 12 Oct 2000 13:08:19 -0500 | From | Jeff Epler <> | Subject | Re: large memory support for x86 |
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On Thu, Oct 12, 2000 at 10:36:38AM -0700, Kiril Vidimce wrote: > Allocate = malloc(). The process needs to be able to operate on >4 GB > chunks of memory. I understand that it's only a 32 bit address space > which is why I was surprised when I read that Linux 2.4.x will support > upwards of 64 GB's of memory. > > Thanks for all the responses.
Pointers are still 32 bits on x86, and the visible address space for any particular process is still somewhat less than 4G.
I believe that if you select Linux on Alpha that you can have more than 4G per process, but that may or may not be true.
What the support for >4G of memory on x86 is about, is the "PAE", Page Address Extension, supported on P6 generation of machines, as well as on Athlons (I think). With these, the kernel can use >4G of memory, but it still can't present a >32bit address space to user processes. But you could have 8G physical RAM and run 4 ~2G or 2 ~4G processes simultaneously in core.
There may or may not be some way to support an abomination like the old "far" pointers in DOS (multiple 4G segments), but I don't think it has been written yet.
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