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Date: Mon, 19 Aug 2013 13:09:36 +0200
From: Laszlo Ersek <lersek@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v3 1/2] memory: export migration page size
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>

On 08/19/13 12:21, Peter Maydell wrote:
> On 19 August 2013 10:59, Laszlo Ersek <lersek@redhat.com> wrote:
>> On 08/13/13 00:43, Michael S. Tsirkin wrote:
>>> Migration code assumes that each RAM block is a multiple of target page
>>> size.
>>
>> Isn't that a valid assumption, considering the TARGET_PAGE_ALIGN() macro
>> call in qemu_ram_alloc_from_ptr() [exec.c]?
> 
> That macro only makes the size we store in the ramblock data
> structure be a multiple of the page size -- it does nothing to ensure
> that the actual memory that was passed in by the caller is the
> right size. (It will have the right effect where qemu_ram_alloc_from_ptr
> is allocating the memory itself, obviously.)

Which is the case for 2/2, see my comments there:

memory_region_init_ram()
  qemu_ram_alloc()
    qemu_ram_alloc_from_ptr()  <---- host==NULL
      TARGET_PAGE_ALIGN()

Laszlo