From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Kadianakis Subject: Re: [PATCH 1/1] SCSI: lpfc, restore MSI-X/MSI support Date: Thu, 14 Jan 2010 19:26:17 +0200 Message-ID: <87aawga98m.fsf@gmail.com> References: <87r5pta66n.fsf@gmail.com> <4B4F4E55.4030206@emulex.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-ew0-f209.google.com ([209.85.219.209]:45539 "EHLO mail-ew0-f209.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751411Ab0ANR1P (ORCPT ); Thu, 14 Jan 2010 12:27:15 -0500 Received: by ewy1 with SMTP id 1so7038ewy.28 for ; Thu, 14 Jan 2010 09:27:10 -0800 (PST) In-Reply-To: <4B4F4E55.4030206@emulex.com> (James Smart's message of "Thu, 14 Jan 2010 12:03:17 -0500") Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Smart Cc: "linux-scsi@vger.kernel.org" James Smart writes: > The short response: > Acked-by: James Smart > > > Background: > Nothing Broke. This was intended. > > We had originally enabled MSI-X by default, but in qualification > within the last 12 months, we encountered a major catch-22: > > There were at least 4 platforms, from 2 major OEMs, that : > - Say they support MSI-X - platform routines work and act as if they do. > - We enable it, generate a test interrupt to check they really do > deliver it, and it works. > - But shortly after attachment, the system hangs or loses interrupts, > resulting in a bad system behavior. > > Given the distro's picking up the 2.6.32 kernel, we had to stick with > a default of MSI-X off, with user-enabled MSI-X as these platforms > couldn't get fixed. > > However, we're also now encountering platforms that require MSI-X and > never INTx, so we must change. It's desired also for also for > performance reasons. > > So - now (2.6.33) is the right time to re-enable MSI-X by default. > > > -- james s > So I see! Thanks for the clarification. It was just that your commit's description didn't mention the interrupt method change at all (and I also couldn't find any information on the internet), and I thought it was accidental. Anyway, all in all, I think that the correct course of action here is to have MSI-X as the default (for the reasons you described) and users with defective systems can enable INTx manually.