Reserve physical page

[Prateek Sharma]

On Sun, Aug 7, 2011 at 9:27 PM, Vladimir Murzin <murzin.v at gmail.com> wrote:

> On Sat, Aug 6, 2011 at 11:36 AM, Prateek Sharma <prateek3.14 at gmail.com>
> wrote:
> > Hello everyone,
> >    I am wondering whether it is possible to reserve a particular physical
> > page in the kernel.
> > The GFP pages can start from _any_ location, and i cannot find a way to
> > specify a starting pfn.
> > I need a few dozen pages to store a bitmap starting at a particular
> physical
> > page frame number.
> >    Perhaps i am trying to do this wrong? I am trying to establish a
> > (one-way) communication between KVM and a guest VM, by assuming that if
> KVM
> > knows the physical address in the VM , it can access that bitmap.
> >
> >   Thanks !
> >
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> >
> >
>
> Hi Prateek!
>
> I'm not completely sure, but why don't you hide needed page from
> kernel? I mean, you can provide kernel with memory layout
> configuration through mem= boot option. You can, for instance, use
> mem=32768K at 0K,mem=32764K at 32772K, i.e. you tell to kernel  there is a
> gap (starting at 32768K from 0x0 in 4K size) in memory layout. Later,
> you can use this gap via ioremap call.
>

This looks like it will work. Thank you!
I will try this and report how this little experiment went.

Thanks again,
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