Page fault in kernel code

[Manavendra Nath Manav]

On 10-Sep-2014 6:24 pm, <Valdis.Kletnieks at vt.edu> wrote:
>
> On Wed, 10 Sep 2014 14:45:23 +0530, Manavendra Nath Manav said:
>
> > But if the total RAM is limited (less than 896MB LOWMEM), for example
as in
> > embedded devices how the kernel code be kept in RAM all the time. Am I
> > correct to assume that the kernel pre-fetches all pages when entering
> > kernel mode from user mode?
>
> No, kernel code is loaded by your boot loader, and *it stays there*.
Similarly,
> if you modprobe something, the kernel allocates the page, loads the code,
> and leaves it there.
>
> Particularly in embedded devices, where you know all the modules the
kernel may
> need, it's common to just create a kernel with everything built in, no
module
> support, and when the system boots, it loads into memory and never moves
again.
>

Linux kernel memory is not page-able, but memory allocated through vmalloc
can still cause page fault. How device drivers using vmalloc handle this?
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