Talk:Physical Address Extension/Archives/2020/February

As to the PAE kernel for Linux

That is a long and old news that even though the processors, x86 or IA-32, lack support of PAE, could also be equipped with PAE kernel. As to the further information, one could retrieve such information from Linux kernel source, from http://www.kernel.org. — Preceding unsigned comment added by 119.53.112.209 (talk) 00:42, 9 May 2017 (UTC)

The only kernels that can run on a processor without PAE support are 1) kernels without PAE support and 2) kernels that check whether the hardware supports PAE, enables it if and only if present, and, depending on whether PAE is enabled or not, use different code to manage page table entries.

If you look at the Linux kernel source, in arch/x86/include/asm/pgtable_32_types.h, you'll see a comment

   /*
    * The Linux x86 paging architecture is 'compile-time dual-mode', it
    * implements both the traditional 2-level x86 page tables and the
    * newer 3-level PAE-mode page tables.
    */

and, in fact, whether the kernel uses pre-PAE or PAE page tables on 32-bit x86 processors is set at compile time, not determined at run time, so a kernel with PAE support will work only on a machine that supports PAE; a kernel without PAE support will work on a machine that supports PAE, but it won't use PAE and will only handle 4GB of physical memory.

So, no, you can't run a PAE kernel on a processor that lacks PAE support; anybody who believes that it does either hasn't read the Linux kernel source or read it but didn't understand it. Guy Harris (talk) 03:34, 9 May 2017 (UTC)

yeah, you are definitely correct! — Preceding unsigned comment added by 119.53.116.164 (talk) 12:50, 9 May 2017 (UTC)

{{Done}}