Date: Wed, 22 Dec 2004 10:09:43 +0800 From: Jun Su <csujun@gmail.com> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: delphij@freebsd.org Subject: Re: Propose for Several Dump types Message-ID: <cd4370cf041221180927295ed2@mail.gmail.com> In-Reply-To: <16835.1939.301128.802993@grasshopper.cs.duke.edu> References: <cd4370cf04121323433255da9d@mail.gmail.com> <16835.1939.301128.802993@grasshopper.cs.duke.edu>
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On Fri, 17 Dec 2004 11:21:39 -0500 (EST), Andrew Gallatin <gallatin@cs.duke.edu> wrote: > > Jun Su writes: > > > Kernel-Only Dump > > ============== > > We now can use /dev/kmem as the core file. If we can generate a dump file with > > the same information with it, then we can enable kernel-only dump with > > very limit code changes. > > > > 1. Change KVM library to support a new type of file that only contains > > kernel memory. > > 2. Change kernel side to write only kernel memory when dumping. > > 3. Change dumpon utility to do the right checking on the partiction size. > > I think the kernel-only dump is an excellent idea. But I'm confused > as to how you would do it. > > To me, it seems like the most obvious way to do this would be walking > the kernel's vm maps. But that does not work on 64-bit platforms which > have a direct 1-1 physical/virtual address mapping. So how do you > quickly distinguish kernel memory from user memory in the dump > routine? I'm probably missing something simple.. My current draft idea is to traverse the vm_map structure. Then I can find out the vm_object list. Then dump those memory regions. I don't understand VM much. In this area, I need input from our VM guru... > > Thanks, > > Drew > > -- -- Jun Su
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