Bug#955232: Please add 9p kernel module to the cloud image.
On Mon, Mar 30, 2020 at 10:33:24AM +0200, Vincent Bernat wrote:
> >> Please consider adding kernel module '9p' to the cloud image. It is
> >> impossible to passthrough filesystem from hypervisor with the current cloud
> >> image and there are no additional packages to install it. The only way that
> >> I know to passthrough filesystem currently is to remove
> >> linux-image-cloud-amd64 and install linux-image-amd64.
> >
> > The "cloud" images are specifically meant for running on public clouds,
> > and don't support everything that could possibly be exposed to a VM.
> >
> > Is there a public cloud that supports 9p passthrough?
>
> Dunno about OP, but for me, it's also useful when using nested
> virtualisation. Also, the limitation to "public" cloud seems quite
> restrictive. Cloud kernel is used by cloud images, which can be used
> directly with libvirt, for example.
The "nocloud" VM images generated by the cloud team use the generic
kernel, and they're what I'd recommend for use with libvirt and similar
systems. The others are targeted toward specific cloud vendors and may
not work entirely as expected outside those environments. Some of the
supported cloud vendors do support nested virtualization and/or
bare-metal host provisioning, so there are cases where 9p could be used
to share data between hosts...
I'm inclined to agree with Ben. The goal of the cloud kernel is not to
support all possible cloud configurations. Host <-> guest filesystem
sharing isn't a super common thing in cloud environments, and the
generic kernel is always available if needed. Its featureset is a
superset of that of the cloud kernel.
Enabling 9p won't result in a drastic increase in the installed size,
but it is something of a slippery slope.
Virtio-fs appears to be the future for this type of use-case, and we do
enable this for bullseye cloud kernels. I'd much rather encourage its
use instead of the crufty old abuse of a network filesystem that is 9p.
noah
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