On Wed, Feb 28, 2018 at 7:56 PM, Benjamin Herrenschmidt <benh@xxxxxxxxxxx> wrote: > On Thu, 2018-03-01 at 14:54 +1100, Benjamin Herrenschmidt wrote: >> On Wed, 2018-02-28 at 16:39 -0700, Logan Gunthorpe wrote: >> > Hi Everyone, >> >> >> So Oliver (CC) was having issues getting any of that to work for us. >> >> The problem is that acccording to him (I didn't double check the latest >> patches) you effectively hotplug the PCIe memory into the system when >> creating struct pages. >> >> This cannot possibly work for us. First we cannot map PCIe memory as >> cachable. (Note that doing so is a bad idea if you are behind a PLX >> switch anyway since you'd ahve to manage cache coherency in SW). > > Note: I think the above means it won't work behind a switch on x86 > either, will it ? The devm_memremap_pages() infrastructure allows placing the memmap in "System-RAM" even if the hotplugged range is in PCI space. So, even if it is an issue on some configurations, it's just a simple adjustment to where the memmap is placed.
