RE: [E1000-devel] 82571EB: Detected Hardware Unit Hang

The only EEPROM I know about or can speak to is the one attached to the 82571 and it doesn't set the MaxPayloadSize. That's done by the BIOS.

Todd Fujinaka
Technical Marketing Engineer
LAN Access Division (LAD)
Intel Corporation
todd.fujinaka@intel.com
(503) 712-4565


-----Original Message-----
From: Joe Jin [mailto:joe.jin@oracle.com] 
Sent: Wednesday, November 28, 2012 12:31 AM
To: Ben Hutchings
Cc: Fujinaka, Todd; Mary Mcgrath; netdev@vger.kernel.org; e1000-devel@lists.sf.net; linux-kernel@vger.kernel.org; linux-pci
Subject: Re: [E1000-devel] 82571EB: Detected Hardware Unit Hang

On 11/28/12 02:10, Ben Hutchings wrote:

On Tue, 2012-11-27 at 17:32 +0000, Fujinaka, Todd wrote:

quoted

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).

Ben,

Unfortunately I'm using 3.0.x kernel and this is not included in the kernel.
So I'm trying to use ethtool modify it from eeprom to see if help or no.


Todd, I'll review all MaxPayload for all devices, but need to say if it mismatch, customer could not modify it from BIOS for there was not entry at there, to test it, we have to find how to verify if this is the root cause, so still need to find the offset in eeprom.

Thanks in advance,
Joe