On Fri, 22 Nov 2013 15:23:56 +0100 Gerd Hoffmann <kra...@redhat.com> wrote:
> On Do, 2013-11-21 at 03:38 +0100, Igor Mammedov wrote: > > Add DimmBus for memory hotplug below 4Gb or above 4Gb depending > > on initial memory size and hotplug memory size. > > > > * if ram_size is less than 32-bit PCI hole start, reserve > > hotplug memory region as [ram_size,32bit-PCIhole-start) > > if hotplug memory region fits there, > > otherwise reserve hotplug memory region after "0x100000000ULL > > + above_4g_mem_size" > > Hmm, 32-bit pci hole start depends on ram size ... > > 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. 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? I'm now experimenting with removing pci-info and allowing BIOS to do placement of 32-bit PCI bars akin it was done with 64-bit BARs, (I'm looking to using E820 reservations for it but I'm not sure it will work with every guest OS, so it needs more testing). > cheers, > Gerd > > >
