Re: Kernel Dump

From: Peter Wemm (peter_at_wemm.org)
Date: 06/24/05

  • Next message: Peter Wemm: "Re: How to get stack from every thread when doing crash dump?" 
    To: obrien@freebsd.org
Date: Thu, 23 Jun 2005 18:01:43 -0700

    On Thursday 23 June 2005 06:53 am, David O'Brien wrote:
    > On Wed, Jun 22, 2005 at 11:23:25PM -0700, Peter Wemm wrote:
    > > IA64 and Sparc systems usually had sparse memory configurations and
    > > the old raw format didn't have any facility to avoid storing holes.
    >
    > ..
    >
    > > I've just rewritten the AMD64 crashdump support to use ELF like
    > > ia64. In fact, I reused most of the ia64 code. We ran into serious
    > > problems at work, first on the amd64 platform and now also the i386
    > > platform. The problem is that x86 machines are increasinly having
    > > memory holes. The simplistic dump code has no way to skip the
    > > memory hole and tries to dump things like the AGP frame buffer, pci
    > > card MMIO space, PCI-Express configuration space (this means
    > > accessing hardware!!) and so on.
    >
    > Hi Peter,
    >
    > This is great news! I'm really happy to see this work. Will we be
    > able to switch to this for 6.0R?

    I'd very much like for this to happen. I've been testing primarily with
    amd64, but Paul Saab is doing a quick port to i386 (should be trivial).

    The good news is that the libkvm impact is pretty much trivial. I was
    pleasantly surprised.

    There'll be patches to look at shortly.

    BTW: It turns out that sparc64 uses its own custom dump format. It uses
    a custom region descriptor instead of elf's core dump chunk
    descriptors. I believe it also passes a pointer to its kernel page
    table. 

    -- 
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5
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