On Wed, Feb 28, 2018 at 7:56 PM, Benjamin Herrenschmidt
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.