Reserve physical page

[Vladimir Murzin]

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.