Re: [PATCH] Reserve device ID 51 for Virtio HAB (Host-Guest Auxiliary Bridge) device

Hi all,

Gentle ping on this patch.

The earlier questions have been addressed in the thread. Could anyone comment
on whether there are any remaining concerns with reserving Device ID 51 for
Virtio HAB?

I'd be happy to provide additional details if needed.

Thanks for your review.

Best regards,
Zelong

On Mon, 7 Jul 2026, Zelong Ren wrote:
>
> > Can this be used for communication between two different guest VMs?
>
> We didn't have this use case today but with some effort this can be supported.
> It should be viewed as 2 GVMs still requires the setup of PVM and assistance
> of it to reach this functionality.
>
> > Do you plan to upstream the specification for this device as well?
>
> Yes, agree 100%.
> The ID reservation is the first step, we plan to upstream the device specification
> to the virtio TC as well.
>
> On Thu, 2 Jul 2026, Demi Marie Obenour wrote:
> >
> > > Virtio HAB device is an inter-VM IPC and shared-memory device
> > > intended for multi-VM systems.
> > >
> > > Virtio HAB provides named service channels between guest VMs
> > > and primary/service VM, primarily targeting platform-specific
> > > hardware accelerators and system services (deployed in Qualcomm
> > > automotive platforms).
> >
> > Can this be used for communication between two different guest VMs?
> >
> > > It also supports bi-directional zero-copy shared-memory lifecycle
> > > operations (export/unexport/import/unimport).
> > >
> > > The driver is shipping in Qualcomm automotive IVI products,
> > > supports Gunyah, QNX, Green Hills, Red Bend and Xen hypervisors
> > > (KVM in progress), and is being prepared for Linux kernel upstreaming.
> > >
> > > Signed-off-by: Zelong Ren <[email protected]>
> > > ---
> > >  content.tex | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/content.tex b/content.tex
> > > index 243ce2d..25837d8 100644
> > > --- a/content.tex
> > > +++ b/content.tex
> > > @@ -805,6 +805,8 @@ \chapter{Device Types}\label{sec:Device Types}
> > >  \hline
> > >  50         &   Video encoder/decoder device \\
> > >  \hline
> > > +51         &   HAB (Host-Guest Auxiliary Bridge) device \\
> > > +\hline
> > >  \end{longtable}
> > >
> > >  Some of the devices above are unspecified by this document,
> >
> > Do you plan to upstream the specification for this device as well?