help with loading core files

Jan Kratochvil jan.kratochvil@redhat.com
Wed Jul 28 12:24:00 GMT 2010


On Wed, 28 Jul 2010 11:06:22 +0200, Steffen Dettmer wrote:
> On Thu, Jul 22, 2010 at 8:18 PM, Jan Kratochvil
> <jan.kratochvil@redhat.com> wrote:
> > I have only experience with virtual machines (qemu-kvm, see
> > savevm and loadvm) where you can snapshot the whole virtual
> > machine with the debugger + debuggee.
> 
> ohh, this sounds like a great idea!
> 
> How long does it approximately take to prepare such a `retry'?
> Is it a matter of very few seconds only?

Yes, ctrl-alt-2, "loadvm a", ctrl-alt-1 takes about 1 second, "savevm b" takes
~3 seconds.  See: http://wiki.qemu.org/download/qemu-doc.html#vm_005fsnapshots

If you run qemu-kvm by hand it does some fsync() by default (#$!@#$!@#), you
should mount your disk using: -drive file=test.qcow2,cache=writeback

Use recent host Linux kernel, older kernels had buggy debug registers in KVM.
Run testsuite in your guest: http://sourceware.org/systemtap/wiki/utrace/tests


Regards,
Jan



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