David Guntner wrote: > Scott Ferguson grabbed a keyboard and wrote: > > erosenberg@hygeiabiomedical.com wrote: > >> I am running 32 bit sid with a pae kernel. What is the maximum RAM that > >> can be used? > > > > 64GB > > Really? As I understand it, a 32-bit operating system cannot address > more than 4G of memory. > > What am I missing here? Read all about PAE (Physical Address Extension) here: https://en.wikipedia.org/wiki/Physical_Address_Extension The hardware actually has more than 32-bits for physical memory addressing. It is actually a 36-bit addressing machine. That is why it is an address extension. But only the operating system kernel has access to those extra address bits. Programs do not. This allows the system _kernel_ to address more than 32-bits of memory. The kernel could address up to 64G. However _programs_ are still limited to 32-bits. In practice an individual program is limited to either 2G or 3G depending upon how it is compiled and linked. But if the system has more memory then many 2G programs could be running at one time consuming more than the 4G total that a 32-bit operating system would be limited to. You could run Firefox and still have system memory available for something else! :-) Bob
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