On Tue, 25 Aug 2015 01:43:50 -0400 (EDT), Tixy wrote: > > Wikipedia, that font of all wisdom, says of NX [1] > ... > [1] https://en.wikipedia.org/wiki/NX_bit
>From that same article, the section on the Linux kernel says this: > > The support for this feature in the 64-bit mode on x86-64 CPUs was > added in 2004 by Andi Kleen, and later the same year, Ingo Molnar > added support for it in 32-bit mode on 64-bit CPUs. These features > have been in the stable Linux kernel since release 2.6.8 in August 2004. > > The availability of the NX bit on 32-bit x86 kernels, which may run > on both 32-bit x86 CPUs and 64-bit x86 compatible CPUs, is significant > because a 32-bit x86 kernel would not normally expect the NX bit that > an x86-64 processor supplies; the NX enabler patch ensures that these > kernels will attempt to use the NX bit if present. So it looks like you're right. The NX feature can be used only when running a 32-bit kernel in PAE mode on a 64-bit processor. When running a 32-bit kernel in PAE mode on a 32-bit processor, the NX bit is not available. So I'm back to my original question. For a system with a 32-bit processor and less than 4G of RAM, what does running a PAE kernel buy me? I can understand why commercial Linux distributions want to eliminate a non-PAE kernel: it's one less kernel to support, and therefore higher profits. But what does running a PAE kernel on a 32-bit system with less than 4G of RAM do for *me*? All I see it doing is making the kernel bigger and chewing up more RAM. -- .''`. Stephen Powell <zlinux...@wowway.com> : :' : `. `'` `-
