From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Byrne Subject: Re: xen-unstable on HP dc7800 simply reboots Date: Tue, 23 Oct 2007 16:03:01 -0700 Message-ID: <471E7DA5.1060603@hp.com> References: <471E485A.2030707@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <471E485A.2030707@hp.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: xen-devel List-Id: xen-devel@lists.xenproject.org John Byrne wrote: > Keir Fraser wrote: >> On 23/10/07 17:49, "John Byrne" wrote: >> >>> Does anyone know what is wrong or can tell me how to go about debugging >>> this? The dmesg output from booting the Ubuntu 2.6.22-14-server kernel >>> is attach in the hope that it will provide some useful information. >> >> I suggest binary-chopping to find the offending changeset. Some early >> boot-time stuff went in over the past few days, so for example try >> reverting >> to 16130 and see if that has the same problem. Go back another 30, or >> forward 15, changesets depending on whether that works or not. I suspect >> this issue is quite new, so it shouldn't take too long to narrow down. > > Actually, it a few months old. xen-unstable 15236 is the last changeset > that Xen doesn't immediately reboot. > Littering the early boot code with putc() and comparing the code's behavior on a machine that actually boots, I've found that the call to get_memory_map from trampoline.S is the root of all evil. If that is called, then the trampoline fails to make it back to protected mode from real mode. I am still working to identify the specific problem. John