Date: Fri, 17 Dec 2004 11:21:39 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Jun Su <csujun@gmail.com> Cc: delphij@freebsd.org Subject: Re: Propose for Several Dump types Message-ID: <16835.1939.301128.802993@grasshopper.cs.duke.edu> In-Reply-To: <cd4370cf04121323433255da9d@mail.gmail.com> References: <cd4370cf04121323433255da9d@mail.gmail.com>
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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.. Thanks, Drew
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