Re: [Qemu-devel] [RESEND PATCH] pc: allow raising low memory via max-ram-below-4g option

[Eduardo Habkost]

On Wed, Jun 01, 2016 at 03:02:56PM +0200, Paolo Bonzini wrote:
> On 01/06/2016 14:28, Gerd Hoffmann wrote:
> > This patch extends the functionality of the max-ram-below-4g option
> > to also allow increasing lowmem.  Use case: Give as much memory as
> > possible to legacy non-PAE guests.
> > 
> > While being at it also rework the lowmem calculation logic and add a
> > longish comment describing how it works and what the compatibility
> > constrains are.
> 
> Does this break migration if you use something like "-M
> max-ram-below-4g=4g -m 3968m"?
> 
> I don't have big problems with that, but it has to be documented.

>From reading the previous discussion, it looks like it breaks
compatibility for:
  gigabyte_align && max_ram_below_4g > 3G || max_ram_below_4g > 3.5G

My past self said that those were unsupported configurations (but
I didn't verify his claim), so it should be OK. But we need to
document that in the commit message, at least.

-- 
Eduardo