Today, we calculate a gap in the low 32bit address space for PCI devices to assign MMIO resources for hotplug or unconfigured devices, (pci_mem_start). This gap calculation is done by walking the e820 memory space, this calculation ignores the SRAT for any possible reservations that the BIOS might have done for memory hotplug. In some cases the PCI device resources (f.e. Expansion ROMS) end up sharing the address space with memory hotplug capable regions. As a result, when we try to hotadd memory to a system which has less than 4GB memory to start with, we see resource clashes and the hotadd requests fail. The solution here is to find a PCI gap in the PCI reserved regions as exported by the ACPI table. We read the _CRS object under PCI0 for possible producer regions and search for a big enough unclaimed gap within these producer regions. There are 2 patches 1. cleanup of the e820_search_gap function 2. code which walks ACPI resources searching for gap within producer regions. I have kept the original e820_find_gap function since in systems with ACPI disabled we still may need to calculate the gap. Please have a look. Thanks, Alok -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
