[Libguestfs] error/crash on mount

[Richard W.M. Jones]

On Tue, Sep 05, 2017 at 10:51:54PM +0100, http_error_418 wrote:
> Hi,
> 
> I am having issues with libguestfs; I am unable to mount a disk either
> from cli or via python bindings. This was working previously, but in
> order to have access to python3.5 I am trying to upgrade from Debian
> 8/Jessie to Debian 9/Stretch. Unfortunately the libguestfs error is
> getting in the way. Output of libguestfs-test-tool is attached as per
> libguestfs.org help.

The error is:

> qemu-system-x86_64: /build/qemu-rymjPd/qemu-2.8+dfsg/target-i386/kvm.c:1805: kvm_put_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed.

This is a kernel problem.  There is some discussion on this bug:

  https://bugs.launchpad.net/qemu/+bug/1661386

Are you running libguestfs on top of VMware?

It appears there's some dispute over exactly who is to blame for the
problem, but you may be able to work around it by using QEMU's
software emulation instead of KVM:

  export LIBGUESTFS_BACKEND_SETTINGS=force_tcg
  (http://libguestfs.org/guestfs.3.html#force_tcg)

Rich.

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