On Thursday 10 January 2013, Thierry Reding wrote: > On Wed, Jan 09, 2013 at 04:17:58PM -0700, Jason Gunthorpe wrote: > > On Wed, Jan 09, 2013 at 04:12:31PM -0700, Stephen Warren wrote: > > You could decrease the size of the mapping to only span the bus > > numbers that are configured for use via DT. > > That won't work, unfortunately. The mapping is such that the bus number > is not encoded in the uppermost bits, the extended register number is. > So the only thing that we could do is decrease the size of the extended > register space for *all* devices. But you could still a method to map 16 separate areas per bus, each 65536 bytes long, which results in 1MB per bus. That is probably ok, since very few systems have more than a handful of buses in practice. In theory, doing static mappings on a per-page base would let you do 16 devices at a time, but it's probably worth doing at this fine granularity. > > Are there any concerns about these config registers being accessed > > from a context where a new mapping can't be made? Interrupt? Machine > > Check? PCI-E Advanced Error Reporting? > > I haven't checked but I would expect configuration space accesses to not > happen in interrupt context. Usually they are limited to enumeration and > driver probe. Actually, AER probably needs this, and I believe some broken devices need to mask interrupts using the PCI command word in the config space, it it can happen. 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
