From owner-freebsd-current@FreeBSD.ORG Sat Aug 25 19:52:37 2007 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2595416A41B for ; Sat, 25 Aug 2007 19:52:37 +0000 (UTC) (envelope-from kip.macy@gmail.com) Received: from nf-out-0910.google.com (nf-out-0910.google.com [64.233.182.191]) by mx1.freebsd.org (Postfix) with ESMTP id 993C613C48A for ; Sat, 25 Aug 2007 19:52:36 +0000 (UTC) (envelope-from kip.macy@gmail.com) Received: by nf-out-0910.google.com with SMTP id b2so933899nfb for ; Sat, 25 Aug 2007 12:52:35 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=t/5yo0xJ05u+PoWw9i19Jdl7V49TMkRZ/xkNaHmGejXEjgtCGYzE1L6raJyESjZoMEDs+H+mgdb0RLNLI0oqRJGSGpyQUmpjcKeCCA37R3LsFUZPLhqVvnff0pT7HcY3KoRzvPu+HhhqtjbGcaC2nXa9HOuYptIo7rnCysUtN54= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=uE8m+P51r2U3djt16Ls0+/2NfiOCgo3J32Cu8o6N5EPH9UbZwWyV4SaQFICctPyKfih+ZzDmKHWZuDvukzIQE4lGZ8sDCA5KZUiFIO2uFE3oJzFyQtItNIgtlvA6Lsxy5nLwxUWlFTJ/SWqH70uaRwmw88fe9T887F9OBqETEsQ= Received: by 10.78.193.5 with SMTP id q5mr2691973huf.1188071554477; Sat, 25 Aug 2007 12:52:34 -0700 (PDT) Received: by 10.78.162.18 with HTTP; Sat, 25 Aug 2007 12:52:34 -0700 (PDT) Message-ID: Date: Sat, 25 Aug 2007 12:52:34 -0700 From: "Kip Macy" To: "Andrew Turner" , "Robert Watson" , freebsd-current@freebsd.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20070824181627.57bed401@hermies.int.fubar.geek.nz> <20070824132409.W3900@fledge.watson.org> <20070826000708.15fbb5bb@hermies.int.fubar.geek.nz> Cc: Subject: Re: FreeBSD on xen hvm X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 25 Aug 2007 19:52:37 -0000 On 8/25/07, Kip Macy wrote: > Have you tried gdbserver? Sorry gmail client freaked out. I know that the gdbserver worked with hvm guests at least at one point. Please let me know if that is not the case. -Kip > > -Kip > > > On 8/25/07, Andrew Turner wrote: > > On Fri, 24 Aug 2007 13:30:17 +0100 (BST) > > Robert Watson wrote: > > > On Fri, 24 Aug 2007, Andrew Turner wrote: > > > > > > > 1) PREEMPTION Preemption causes the kernel to panic with a page > > > > fault. The dmesg is available from [1]. > > > > > > Any chance it's possible to get a core for this, or attach GDB > > > somehow to the VM? > > I haven't managed to get either remote GDB working and it's too early > > in the boot for a core. I can get a xen core dump but it would require > > processing to get it into something gdb could use. > > > It looks like timing in Xen may be exposing a > > > race in some or another subsystem with timers, but figuring out which > > > subsystem it is will be most easily done if we can inspect the > > > callout information, which is most easily done with GDB since you can > > > inspect the callout structure more easily. If not, then we can add > > > some printfs to extract the information, I expect, or extend DDB. We > > > need to find out what the function pointer in the callout structure > > > is for. > > I've created a patch at [1] to add "show callouts" to ddb. It prints > > all the callouts in callwheel and the name of the function they call. > > The callouts with preemption are: > > loadav > > in6_tmpaddrtimer > > in6_rtqtimo > > in_rtqtimo > > in6_mtutimo > > uma_timeout > > nd6_slowtimo > > nfsrv_timer > > tcp_isn_tick > > scrn_timer > > roundrobin > > atkbd_timeout > > sleepq_timeout > > sleepq_timeout > > sleepq_timeout > > sleepq_timeout > > pffasttimo > > pfslowtimo > > kbdmux_kbd_intr_timo > > if_slowtimo > > ipport_tick > > nd6_timer > > lboltcb > > tcp_hc_purge > > > > Preemption does not always cause the kernel to panic, however when it > > doesn't it shows the mountroot> prompt and is unable to load the root > > as no disk drives show up. > > > > > > > 3) INVARIANTS Invariants causes a panic from a page fault. See [2] > > > > for the dmesg and backtrace. > > > > > > This appears to be in the start up of Audit as it creates a kernel > > > thread. Possibly it's creating the thread too early, or possibly > > > something else is going on. Can you try creating a kernel without > > > options AUDIT and see if it works better, or if it just panics when > > > the next thread is created? > > It just panics in the next thread created. > > > > > > It sounds like Xen may start the timer firing sooner than on plain > > > hardware, or possibly at a faster rate initially, and that's causing > > > things to happen in a different order, so I expect we'll either bump > > > into a series of races of this sort based on different ordering of > > > events, or discover the timer isn't properly being disabled or > > > managed in Xen :-). > > I'm suspecting the timer isn't being managed properly. The timer in the > > loader always stays at 10 and with DIAGNOSTIC I'm getting lines like: > > Expensive timeout(9) function: 0xc097da70(0xc0bbaa00) -1.982636062 s > > > > Andrew > > > > [1] http://fubar.geek.nz/files/freebsd/ddb-callout.diff > > > > -- > > Andrew Turner > > http://fubar.geek.nz/blog/ > > _______________________________________________ > > freebsd-current@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-current > > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" > > >