On Mon, Dec 22, 2008 at 1:03 AM, Mike McMullin
Ok, on 11.0 the pae kernel install seems to have been a mistake, but on the two 11.1 install, both have been pae kernels, which leavse me wondering why a simple 32bit AMD Athlon system requires anything other than the default kernel.
PAE stands for Physical Address Extension. It was introduced in the Pentium Pro and basically changes the process to use a 36bit memory address size. This allows you to use up to 64GB on a 32bit system. See here: http://en.wikipedia.org/wiki/Physical_Address_Extension Generally, this isn't very relevant outside of servers that have more than 4GB of RAM. Also, it enables the NX or XD bit to be enabled like Marcus pointed out. The NX bit is bit 63, so you have to have access to that space to use it. As for why it is enabled by default on 32bit systems, from my understanding it is so that if your processor supports the NX bit, like 64bit cpus and the intel Core Solo and Core Duos, then it can be enabled. If you don't have these processors, or more than 4GB RAM, then there should be no reason why you can't run the default kernel. However, I don't think that the PAE stuff takes up any space or cycles if you don't have the RAM or NX bit, so it shouldn't be a problem. The Default Kernel would be required for a Pentium or K6 chip. Here's a quote: Another example, BTW, is PAE. You'd think that, since all Intel processors since Pentium Pro supported PAE, CPUs that does not support PAE would be nowadays be completely obsolete. Except that AMD's CPUs did not implement PAE until the Athlon, and VIA's CPUs did not support PAE until VIA C7, and Transmeta's older Crusue CPU did not support PAE, only the newer Efficion did support PAE. In fact even AMD's own Geode GX and LX and versions of Intel's own Pentium M and Celeron M without NX support did not support PAE! I think NX was what pushed VIA and Transmeta to add PAE support into their CPUs. Also even if the CPU problem were solved, I am sure there are some buggy BIOSes that can crash when PAE is on. That is why most Linux distros does not make the PAE kernel the default just to take advantage of NX. Windows by default automaticly select a kernel based on whether PAE is going to be on or not, Linux can't do this. BTW, see this blog article for more info on the relationship between PAE and NX in Windows XP SP2 and later: http://yuhong386.spaces.live.com/blog/cn.. from here: http://www.virtualdub.org/blog/pivot/entry.php?id=30 -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org