On Sun, Aug 7, 2011 at 9:27 PM, Vladimir Murzin [off-list ref] wrote:

On Sat, Aug 6, 2011 at 11:36 AM, Prateek Sharma [off-list ref]
wrote:

quoted

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

quoted

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

quoted

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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