From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: Fresh install of Windows XP hangs early in boot? Date: Tue, 29 Jul 2008 19:57:34 -0300 Message-ID: <20080729225734.GA15606@dmt.cnet> References: <20080729212332.GA8331@dmt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm-devel To: Roland Dreier Return-path: Received: from mx1.redhat.com ([66.187.233.31]:38931 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754061AbYG2W6d (ORCPT ); Tue, 29 Jul 2008 18:58:33 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Jul 29, 2008 at 03:00:06PM -0700, Roland Dreier wrote: > > Known problem: > > http://www.nabble.com/LSI:-avoid-infinite-loops-p17116605.html > > > Windows driver has scripts code which busy loops on main memory. Since > > that executes in vcpu context, the cpu won't ever get a chance to change > > the variable which the SCSI emulation is looping at. > > Thanks Marcelo (and Alberto) for pointing me at this. > > > The proposed hack, however, is half-assed (see Paul Brook's comments on > > that thread). > > I'd be willing to take a stab at a better fix. Awesome! That would be very welcome. It is quite important for better-than-IDE performance with Windows guests. > Is there any documentation about the lsi microcode engine anywhere? http://www.lsi.com/files/docs/techdocs/storage_stand_prod/SCSIControllers/56_3.pdf > Would the right fix to be to detect the busy loop on CPU memory and > return from lsi_execute_script() in that case? Detect the busy loop, interrupt script execution but guaranteeing that it will continue (by starting a timer to restart execution some time in the future, for example). The tricky part is that in between, SCRIPTS execution could have been restarted by the guest via PIO/MMIO, or by an I/O completion event, so proper synchronization is needed. The hack I did relied on the driver to restart execution by Signal Process command (SIGP), but its possible that such command would never be sent (as Paul Brook mentions in the thread). > BTW I tried using if=ide to install Windows XP and got a blue screen > during the installer. What are people doing to run XP in a kvm guest? Are you using a recent version of kvm-userspace/kernel modules? Please save the blue screen and mail it to the list or fill a bug. Thanks