Re: [Qemu-devel] [PATCH 1/1] pc & q35: fix handling of lowmem

[Don Slutz <dslutz@verizon.com>]

On 02/28/14 08:35, Gerd Hoffmann wrote:
> On Do, 2014-02-27 at 15:01 -0500, Don Slutz wrote:
>> Without this, asking for 3.25G on memory for pc-i440fx-2.0 does not
>> adjust the pci hole to start at 3G.  Asking for 3.75G does do this
>> adjustment.
> This is intentional.
>
> If we can fit all ram into low memory, because it is less than 3.5G,
> we'll do that (pc machine type, q35 numbers are different but logic is
> the same).  This way 32bit (+non-PAE) guests can continue to have up to
> 3.5G memory.
>
> If we can't fit all ram into low memory (thus the guest should be able
> to access ram above 4G anyway), then we'll cut off at a gigabyte
> boundary (3G for pc machine type).  This way our ram is nicely
> gigabyte-aligned and we can get best performance benefits from huge
> pages.
>
> The size of the pci hole changing in the second case is only a side
> effect, it's not the main reason for the change.
>
> cheers,
>    Gerd
>
>
Ok, I will drop this patch.
     -Don Slutz