From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753801AbYIFQGS (ORCPT ); Sat, 6 Sep 2008 12:06:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751568AbYIFQGJ (ORCPT ); Sat, 6 Sep 2008 12:06:09 -0400 Received: from rv-out-0506.google.com ([209.85.198.231]:40005 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbYIFQGH (ORCPT ); Sat, 6 Sep 2008 12:06:07 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=LyX3O2lf8zLQBeD5uQEDBwJ9Htly6q1PQSjl8YyFFlEvXYmd73gJvf0COizJE/0e+H BHW4i5zoziM96iojOGll2d2cO4Br4HwV1w2Z65k0rQYWEF3DZ2595uQi9WxB97AvfwL1 fKJVg/hxKcGVgUVuaV+ayNBPOjg8yM57ax6wo= Message-ID: <86802c440809060906h721d6243t4a3b5fb604a9d7b3@mail.gmail.com> Date: Sat, 6 Sep 2008 09:06:06 -0700 From: "Yinghai Lu" To: "Ingo Molnar" Subject: Re: [2.6.27] overlapping early reservations [was: early exception - lockdep related?] Cc: "Luca Tettamanti" , "H. Peter Anvin" , "Peter Zijlstra" , linux-kernel@vger.kernel.org, mingo@redhat.com In-Reply-To: <20080906145122.GA7693@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <68676e00809051217h3da02a6bld4412b4a2ee3b728@mail.gmail.com> <1220642738.11202.21.camel@twins.programming.kicks-ass.net> <48C19415.9060108@kernel.org> <68676e00809060620k35679302s42fc0a74aa1dc2d3@mail.gmail.com> <20080906145122.GA7693@elte.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 6, 2008 at 7:51 AM, Ingo Molnar wrote: > > * Luca Tettamanti wrote: > >> On Fri, Sep 5, 2008 at 10:18 PM, H. Peter Anvin wrote: >> > Peter Zijlstra wrote: >> >> >> >> On Fri, 2008-09-05 at 21:17 +0200, Luca Tettamanti wrote: >> >>> >> >>> On Thu, Sep 4, 2008 at 10:51 PM, Luca Tettamanti >> >>> wrote: >> >>>> >> >>>> On Thu, Sep 4, 2008 at 4:25 PM, Peter Zijlstra >> >>>> wrote: >> >>>>> >> >>>>> Sadly your config just boots, albeit not to userspace due to missing >> >>>>> drivers. >> >>>> >> >>>> Yes, I managed to boot it with qemu... I tried kgdb - without luck - >> >>>> kernel dies too early. >> >>>> I also managed to get a stack trace :D >> >>>> >> >>>> http://img151.imageshack.us/my.php?image=tracedm1.jpg >> >>>> >> >>>> It seems that lockdep is an innocent bystander... the kernel died with >> >>>> panic() in __reserve_early, and then took another exception while >> >>>> printing the panic (I guess). >> >>>> Will add further debug stuff to see wtf is going on. >> >>> >> >>> Hum, kernel says: >> >>> >> >>> http://img177.imageshack.us/my.php?image=overlappingus2.jpg >> >>> >> >>> Overlapping early reservations b98000-eff266 RAMDISK to 200000-d09cf7 >> >>> TEXT DATA BSS >> >>> >> >>> It would appear that the initramfs is overlapping the kernel itself, >> >>> is the boot loader (LILO) doing something stupid? >> >> >> >> Suppose it is, lets ask hpa.. >> >> >> > >> > It definitely looks like it. >> >> Is there anything that the kernel could to do confuse lilo? The issue >> started appearing with 2.6.27 and the outcome of the boot process >> varies between versions and seems sensitive to configuration changes >> (though a "bad" kernel consistently fails). > > good question. Does your successful 2.6.26 bootup actually _depend_ on > the initrd? Or does it perhaps have enough built-in drivers that make it > boot just fine? > > in that case v2.6.26 might just have stomped on the initrd silently, > corrupted it (during kernel decompress), and the initrd unpacker saw the > corruption and ignored it. Userspace wouldnt care as the kernel had all > the drivers it needed. > > or perhaps something made your v2.6.27 bzImage larger so that the > overlap happens - while it didnt before. > >> Orthogonal to my problem: the panic() in reserve_early is useless for >> debugging since the output won't reach the screen or the serial >> console (even worse: the kernel takes an exception while trying to >> execute the panic). Is it acceptable to replace it with an >> early_printk + hlt? > > very much so. I was wondering about that already. console=uart8250,io,0x3f8,115200n8 could help YH