On Mon, 2006-06-12 at 13:32 +0200, Per Jessen wrote:
Would a Linux application even be able to use PAE by itself? Does the kernel provide that option/interface?
Yes. It's really a _complex_ discussion. And my answer below is _still_ a _mega_-simplification. On x86, the kernel has various code to do this, along with GCC compile-time/directives. Applications that want to address more than 1-3GiB (depending on the model) of user-space memory have to be built differently. It's _never_ a matter of getting access to _all_ 4GiB of memory, even if the pointers are capable of (or being rationalized to) address upto 32-bit/4GiB. This is in _addition_ to how the kernel-processor actually do PAE (36-bit) -- which is a _serious_ performance hit. On x86-64, the kernel does even a crapload more. It provides the new "flat" 64-bit address model to the "Long Mode" 48-bit/256TiB pointer model, as well as uses a 7-layer PAE mode (52-bit). So _all_ programs can use it -- flat 32-bit to 1/2/3GiB user, >4GiB x86 object code, as well as new 48-bit "Long Mode" applications. There is also a major reduction in performance hit for even legacy apps built against the old PAE (36-bit) model. -- Bryan J. Smith Professional, technical annoyance mailto:b.j.smith@ieee.org http://thebs413.blogspot.com ------------------------------------------------------- Illegal Immigration = "Representation Without Taxation" -- Check the headers for your unsubscription address For additional commands send e-mail to suse-linux-e-help@suse.com Also check the archives at http://lists.suse.com Please read the FAQs: suse-linux-e-faq@suse.com