From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760761AbZLJX4E (ORCPT ); Thu, 10 Dec 2009 18:56:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759126AbZLJX4D (ORCPT ); Thu, 10 Dec 2009 18:56:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:19583 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758016AbZLJX4B (ORCPT ); Thu, 10 Dec 2009 18:56:01 -0500 Date: Thu, 10 Dec 2009 21:55:50 -0200 From: Mauro Carvalho Chehab To: Jeremy Fitzhardinge Cc: Alan Cox , Keir Fraser , Xen-devel , Linux Kernel Mailing List Subject: Re: Problems with serial interrupts with IPMI 2.0 SoL Message-ID: <20091210215550.7f092006@pedra> In-Reply-To: <4B216C12.1020001@goop.org> References: <4B216C12.1020001@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Thu, 10 Dec 2009 13:45:54 -0800 Jeremy Fitzhardinge escreveu: > Hi, > > I'm using a system with an embedded IPMI 2.0 BMC which provides SoL > (Supermicro X8SIL-F). This works fine under Linux (fully interrupt > driven), but fails for Xen as it appears to not be sending interrupts; > it works OK if I set the driver to polling mode. > > I'm assuming the Xen is tickling some bug in the emulated 16550. The > Linux driver has a couple of pieces of code to explicitly work around > bugs in the Intel AMT SoL implementation, but I don't think they're > coming into play here (because there are no Intel SoL PCI devices on > this system to trigger the NO_TXEN_TEST flag). > > I'm wondering if you have any pointers or suggestions about more subtle > problems? If you don't hit NO_TXEN_TEST flag, you'll be loosing interrupts, as the emulation of 16550 is not perfect. As far as I remember, interrupts take too long to happen with the emulated 16550, when comparing with a normal serial. -- Cheers, Mauro