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Re: [Xen-devel] gdb regression in xen-3.0-testing.hg

At Thu, 22 Jun 2006 12:02:27 +0200,
Simon Kagstrom wrote:
> Hello!
> I recently updated to the latest xen-3.0-testing repository, and since
> then I've had problems with GDB debugging. Only single stepping
> ('step') works, not stepping over function calls ('next') and setting
> breakpoints doesn't work either.
> I've looked in the changelog for changes in tools/libxc and
> tools/debugger/, but I haven't found any changes which would impact
> this (as far as I can see). I've tried to debug libxc a bit, and I can
> see the write of an 'int3' instruction, but it doesn't look like it
> actually happens.

I found the bug. I've used my patch to xc_ptrace.c to reenable
debugging of paravirtualized guests in Changeset 93379554837c
(http://xenbits.xensource.com/xen-unstable.hg?cs=93379554837c), but
forgot the patch to xen/arch/x86/domain.c (to export cr0 to the

This caused cr0 to be zero when the guest context was read by
xc_ptrace, and paging_enabled() therefore doesn't work.

Any chance of changesets 93379554837c, f226a5765c85, dcb66319ed1e
being applied to xen-3.0-testing? Without these, paravirtualized
debugging is still not possible in xen-3.0-testing.

// Simon

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