On Mon, 25 Nov 2013 12:39:05 +0100 Gerd Hoffmann <kra...@redhat.com> wrote:
> > > Does it make sense to hotplug memory above 4g unconditionally to > > > simplify things? > > It does and it was so in v6 RFC, > > But it would rule out hotplug for 32-bit guests that doesn't support > > more then 4Gb. > > Indeed. > > > As use case 32-bit guest could start whit small initial memory > > and hotplug additional memory if needed up to point where 32-bit > > PCI hole starts. That would allow guests to launch with small amount > > but baloon up upto 2-3.5 Gb depending on machine type. > > I could drop 32-bit guest support and do only high mem hotplug if > > this case it not interesting to the comunity, any suggestions? > > 32bit limits start to hurt with 1GB already. Kernel address space is 1G > on 32bit, so the kernel can't map all RAM all the time any more. Which > in turn adds overhead for mapping/unmapping pages if the kernel must > access highmem pages. So it's better to run 64bit guests even with alot > less than 4G of memory. > > I'd tend to just not support 32bit guests, I think it simply isn't worth > the trouble. Fine with me, If there isn't abjection to it, I'll drop 32-bit guest support on the next respin. > cheers, > Gerd > >
