On Friday 03 January 2014, Jason Gunthorpe wrote: > On Thu, Dec 26, 2013 at 04:52:41PM +0100, Thomas Petazzoni wrote: > > > Here is an implementation of this idea, tested to work with an e1000e > > card, with the driver modified to do a few read/write to the I/O > > region. What do you think about it? > > This seems reasonable, the only down side is that a stray read to an > unused portion of the Linux IO mapping will lock the machine instead > of getting a page fault - however I don't see that as a blocker. > I've scratched my head a bit over this patch, and I couldn't find anything wrong with it in the end, as long as we don't have any other device in the system that also wants its share of the I/O space (e.g. a PCMCIA port on the SRAM interface), but then we'd probably need other changes as well. However the part that made me wonder is that an e1000e with a PCI bridge actually /should/not/ need to allocate an I/O space window with a precious mbus resource, since AFAIK this adapter does not have an I/O space BARs. Thomas, can you send the 'lspci -v' output of the system with this card to confirm that the I/O space is actually needed? If not, we should probably review the core PCI code to see why the bridge code tries to add this window. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
