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Re: [Xen-devel] Migrate/Save of 32-bit domU Broken on Xen 3.1.2 64-bit dom0

On 18/1/08 23:29, "Joshua West" <jwest@xxxxxxxxxxxx> wrote:

> Thus, even if I have 32GB of RAM in a server, the total memory that will
> be used in dom0 + all domU's can only add up to 16GB.  Am I just plain
> old wrong?
>> Note that 64-bit Xen + 32-bit Dom0 will support both 32-bit
>> and 64-bit domU's. (Oracle VM uses this configuration by
>> default on 64-bit capable machines.)  And save/restore/migration
>> has been tested to work for this (with the patch Kurt posted).
> Interesting.  For some reason I thought that the Hypervisor had to match
> the dom0's kernel.  So you're saying that if I compile the Xen
> Hypervisor as 64-bit and my dom0 + domU's both as 32-bit, I can reach
> the full capacity of my servers with respect to RAM (32GB) instead of
> being limited to 16GB?  (And this only works with Kurt's patches?).

As long as you run 64-bit Xen you can run 32-bit dom0 and domUs and use the
full memory of your system. The 32-bit guests are not even limited to 16GB
each, let alone jointly. This is true even without Kurt's patches. What
Kurt's patches fix is save/restore/migrate of a 64-bit domU from a 32-bit

 -- Keir

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