Re: [9fans] Memory management questions/not plan-9 specific

["ron minnich" <rminnich@gmail.com>]

On 11/6/07, Robert William Fuller <hydrologiccycle@gmail.com> wrote:
> Paul Lalonde wrote:
> >
> > On Nov 6, 2007, at 10:29 AM, Robert William Fuller wrote:
> >>> In UNIX, set up a signal handler for SIGSEGV.
> >
> > Not quite enough - I still need to reserve some address space.  mmap
> > doesn't let me reserve it without backing it.
>
> It does by default on Linux :-)
>

mmap /dev/zero over the region you want. Or not, you can just any
piece of your address space, actually.

mprotect it (page-aligned, now!0 so you can't access it. record the
fact that you did this. i.e. set up data structures that allow you to
tell, in the segv handler, that it's a "page fault" and not a true
screwup in your code.

in the segv handler, get the fault address and type, search your
structs, figure out what to do. Be sure to compute page frame from the
address, etc. etc. fix it up with memprotect. record what you did.
return.

that's pretty much what I did.

ron