Messages in this thread | | | Subject | RE: [E1000-devel] 82571EB: Detected Hardware Unit Hang | From | Ben Hutchings <> | Date | Tue, 27 Nov 2012 18:10:40 +0000 |
| |
On Tue, 2012-11-27 at 17:32 +0000, Fujinaka, Todd wrote: > Forgive me if I'm being too repetitious as I think some of this has > been mentioned in the past. > > We (and by we I mean the Ethernet part and driver) can only change the > advertised availability of a larger MaxPayloadSize. The size is > negotiated by both sides of the link when the link is established. The > driver should not change the size of the link as it would be poking at > registers outside of its scope and is controlled by the upstream > bridge (not us). [...]
MaxPayloadSize (MPS) is not negotiated between devices but is programmed by the system firmware (at least for devices present at boot - the kernel may be responsible in case of hotplug). You can use the kernel parameter 'pci=pcie_bus_perf' (or one of several others) to set a policy that overrides this, but no policy will allow setting MPS above the device's MaxPayloadSizeSupported (MPSS).
(These parameters are not documented in Documentation/kernel-parameters.txt! Someone ought to fix that.)
Ben.
-- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.
| |