From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59008) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YYZE0-0007YE-S1 for qemu-devel@nongnu.org; Thu, 19 Mar 2015 08:06:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YYZDx-0001dc-Dd for qemu-devel@nongnu.org; Thu, 19 Mar 2015 08:06:56 -0400 Received: from david.siemens.de ([192.35.17.14]:59235) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YYZDx-0001bu-0I for qemu-devel@nongnu.org; Thu, 19 Mar 2015 08:06:53 -0400 Message-ID: <550ABBD4.6050309@siemens.com> Date: Thu, 19 Mar 2015 13:06:44 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <55057FE2.6090604@huawei.com> <5507D3A2.4020502@huawei.com> <1426765305.18873.44.camel@nilsson.home.kraxel.org> In-Reply-To: <1426765305.18873.44.camel@nilsson.home.kraxel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] IO port 0x61 is multiple used List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann , Gonglei , Weidong Huang Cc: "qemu-devel@nongnu.org" , peter.huangpeng@huawei.com On 2015-03-19 12:41, Gerd Hoffmann wrote: > On Di, 2015-03-17 at 15:11 +0800, Gonglei wrote: >> On 2015/3/15 20:49, Weidong Huang wrote: >>> Hi ALL: >>> >>> IO port 0x61 is used by pc speaker and NMI reason port. >>> >>> This is ambiguous. How to distinguish in QEMU? That register is a mess functionality-wise because it serves multiple hardware units that are at least logically separated - legacy. In QEMU, the speaker emulation adopted it as it is the only unit that actually has some functionality behind the bits (see below). >>> >>> I see that NMI reason port is not realized in QEMU. >>> >>> But linux guest will access this port to determine what the NMI reason code means. >>> >>> It will access pc speaker's io port. Is this a bug? >>> >> Gerd, any thoughts? > > Not my area of expertise, but can qemu send NMIs to the guest in the > first place? QEMU doesn't generate the kind of NMI events that would normally be reported via the status bits in port 0x61. Therefore, bits 6 and 7 will always remain unset for now. Jan PS: The port name shown in "info mtree" is wrong. Will send a trivial fix to help identifying the device model behind it. -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux