[libvirt] [PATCH] qemu: Support chardevs with ARM virt machines

[Andrea Bolognani]

On Wed, 2017-06-07 at 23:13 +0200, Christoffer Dall wrote:
> The function to check if -chardev is supported by QEMU was written a
> long time ago, where adding chardevs did not make sense on the fixed ARM
> platforms.  Since then, we now have a general purpose virt platform,
> which should support plugging in any device over PCIe which is supported
> in a similar fashion on x86.
> 
> Signed-off-by: Christoffer Dall <cdall at linaro.org>
> ---
>  src/qemu/qemu_capabilities.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 7f22492..1348af7 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -5507,6 +5507,11 @@ virQEMUCapsSupportsChardev(const virDomainDef *def,
>      if ((def->os.arch != VIR_ARCH_ARMV7L) && (def->os.arch != VIR_ARCH_AARCH64))
>          return true;
>  
> +    /* The virt machine has a PCIe bus and allows plugging in the same type of
> +     * devices as x86 systems do on a PCIe bus. */
> +    if (qemuDomainIsVirt(def))
> +        return true;
> +
>      /* This may not be true for all ARM machine types, but at least
>       * the only supported non-virtio serial devices of vexpress and versatile
>       * don't have the -chardev property wired up. */

We have two bugs tracking this issue:

  https://bugs.linaro.org/show_bug.cgi?id=2777
  https://bugzilla.redhat.com/show_bug.cgi?id=1435681

You mention in [1] that applying this patch and using a
recent QEMU fixes the problem for you, however I can't
say the same: I still get

  -device isa-serial,chardev=charserial0,id=serial0:
  No 'ISA' bus found for device 'isa-serial'

Would you mind sharing your guest XML and the resulting
QEMU command line?


[1] https://bugs.linaro.org/show_bug.cgi?id=2777#c36
-- 
Andrea Bolognani / Red Hat / Virtualization