Re: [Qemu-devel] [PATCH v2] x86: gigabyte alignment for ram

[Michael S. Tsirkin]

On Tue, Dec 17, 2013 at 06:56:06PM +0100, Gerd Hoffmann wrote:
> > I merged your patch but split it: q35 is separate and piix
> > is separate. Would you like me to drop the q35 part then?
> 
> If you are fine with q35 having only 2G lowmem keep it.  It's safe.
> 
> We can sort the mmconfig setup afterwards, then check if (and how) we'll
> transition to 3G lowmem.  Maybe we simply don't after all, with the
> world moving to 64bit it doesn't matter that much whenever memory is
> mapped above or below 4g.  And for old 32bit guests there is always the
> option to stick with piix which continues to offers up to 3.5G lowmem.
> 
> cheers,
>   Gerd
> 

Any update here?
I'm worried 2G lowmem is a bit too aggressive, PAE still exists.
If we want to support old bios, one way would be to add
a new register to enable 3g lowmem.
Or just ignore the issue with new machine types.

-- 
MST