Hi,
On Wed, Jul 11, 2012 at 01:56:19PM +0200, Gerd Hoffmann wrote:
On 07/11/12 12:31, Vasilis Liaskovitis wrote:
In order to hotplug memory between RamSize and BUILD_PCIMEM_START, the pci window needs to start at BUILD_PCIMEM_START (0xe0000000). Otherwise, the guest cannot online new dimms at those ranges due to pci_root window conflicts. (workaround for linux guest is booting with pci=nocrs)
static void pci_bios_map_devices(struct pci_bus *busses) {
- pcimem_start = RamSize;
- pcimem_start = BUILD_PCIMEM_START;
It isn't that simple. For the 32bit pci window it will work, but will leaves address space unused instead of assigning it to the 32bit pci window. For the 64bit pci window it will not work.
You have to walk the dimms and figure what the highest used address is, for both below-4g and above-4g. Then fill two variable with it and make the pci init code use that instead of RamSize and RamSizeOver4G.
I see. I already have these values values computed in qemu-kvm, so I can pass them in a paravirt struct, or infer them from the dimm/srat paravirt info that I already pass to seabios.
If i understand correctly, we would like the pcimem windows to use the maximum possible address space (constrained by the exact dimms/ranges which are defined) instead of leaving unused space.
thanks,
- Vasilis