From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [Qemu-devel] Re: Question about KVM and PC speaker Date: Thu, 07 May 2009 10:12:02 +0200 Message-ID: <4A0297D2.4040009@siemens.com> References: <49EF69BC.90300@gmx.de> <49F01C8D.1010203@web.de> <20090423083252.GB5277@const.bordeaux.inria.fr> <49F031C2.5000204@siemens.com> <20090423092546.GF5277@const.bordeaux.inria.fr> <49F035E7.5080906@siemens.com> <49F03A00.8060502@redhat.com> <49F0430A.8010300@siemens.com> <49FF1919.1030909@gmx.de> <49FF5033.1050402@web.de> <20090504205618.GP5889@const.famille.thibault.fr> <49FF5777.8070704@web.de> <4A006268.6040006@linux-fuer-blinde.de> <3D0ED7CD58CF4D37904670A5A85AE2C7@FSCPC> <4A0167B7.2050200@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Simon Bienlein , Volker Ruppert , Qemu-devel@nongnu.org, kvm@vger.kernel.org To: Sebastian Herbszt Return-path: Received: from lizzard.sbs.de ([194.138.37.39]:15852 "EHLO lizzard.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750754AbZEGIMJ (ORCPT ); Thu, 7 May 2009 04:12:09 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: Sebastian Herbszt wrote: > Jan Kiszka wrote: >> Sebastian Herbszt wrote: >>> Simon Bienlein wrote: >>>> Is a support for BIOS worked on right now? >>> >>> The vgabios (vgabios.c) has a "FIXME should beep". Volker, do you plan >>> to fix this? >>> >>> Which frequency should be used for the beep? Which delay? >> >> I would try 1 KHz and some hundred milliseconds. > > I just looked at some vga bios and it uses about 896,45 Hz. > >>> Getting a delay using "inb(0x61) & 0x10" is still a no go on qemu, >>> right? >> >> Looks like (should be far too inaccurate for longer delays). What about >> 0x40:0x6c, the BIOS' daily timer counter? > > The bios i looked at used the refresh request port 0x61. This is > supported by bochs and > there is also a patch for qemu to replace the dummy [1]. The rombios > uses this to provide > INT 15h AH=86h functionality; this is likely broken with the dummy code > in qemu. I see no problem with improving qemu's emulation accuracy this way a bit. But I wouldn't built new delay implementations on top of it, specifically if the code is in fact aware of running over a hypervisor. Such micro-timings are far too inaccurate for longer delays in an environment where you cannot be sure of running all the time during that period. > > Anyway, using "timer ticks since midnight" should be possible (INT 08h > handler is set up > before vga bios is called). > > [1] http://article.gmane.org/gmane.comp.emulators.bochs.devel/7594 > > - Sebastian > Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux