On Mi, 2013-10-09 at 14:23 +0200, Igor Mammedov wrote:
I'm posting it to get an oppinion on one of possible approaches on where to map a hotplug memory.
This patch assumes that a space for hotplug memory is located right after RamSizeOver4G region and QEMU will provide romfile to specify where it ends so that BIOS could know from what base to start 64-bit PCI devices mapping.
We should think about both pci hotplug and memory hotplug while being at it.
Today the 64bit pci window is mapped right above high memory and is sized (in acpi tables) according to what is needed to map the devices present at boot.
Effect is that there is no extra address space for 64bit bars of hotplugged pci devices. And the window is also in the way when it comes to memory hotplug.
Given that some windows versions don't like the large 64bit windows we should make the window size configurable.
The window location can either be made configurable too, or we simply place it at the top of the address space, with "address space" being what the cpu can address according to cpuinfo.
Current qemu reports this by default:
$ cat /proc/cpuinfo model name : QEMU Virtual CPU version 1.5.3 address sizes : 40 bits physical, 48 bits virtual
40 address lines allow 1TB, so we would place the window just below 1TB.
Comments?
Gerd