Re: [PATCH v3 28/28] docs: update Xen-on-KVM documentation

[Eric Blake]

On Wed, Oct 25, 2023 at 03:50:42PM +0100, David Woodhouse wrote:
> From: David Woodhouse <dwmw@amazon.co.uk>
> 
> Add notes about console and network support, and how to launch PV guests.
> Clean up the disk configuration examples now that that's simpler, and
> remove the comment about IDE unplug on q35/AHCI now that it's fixed.
> 
> Also update stale avocado test filename in MAINTAINERS.
> 
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
> +Xen paravirtual devices
> +-----------------------
> +
> +The Xen PCI platform device is enabled automatically for a Xen guest. This
> +allows a guest to unplug all emulated devices, in order to use paravirtual
> +block and network drivers instead.
> +
> +Those paravirtual Xen block, network (and console) devices can be created
> +through the command line, and/or hot-plugged.
> +
> +To provide a Xen console device, define a character device and then a device
> +of type ``xen-console`` to connect to it. For the Xen console equivalent of
> +the handy ``-serial mon:stdio`` option, for example:
> +
> +.. parsed-literal::
> +   -chardev -chardev stdio,mux=on,id=char0,signal=off -mon char0 \\
> +   -device xen-console,chardev=char0

Is -chardev supposed to appear twice here?

...
> +
> +Booting Xen PV guests
> +---------------------
> +
> +Booting PV guest kernels is possible by using the Xen PV shim (a version of 
> Xen
> +itself, designed to run inside a Xen HVM guest and provide memory management
> +services for one guest alone).
> +
> +The Xen binary is provided as the ``-kernel`` and the guest kernel itself (or
> +PV Grub image) as the ``-initrd`` image, which actually just means the first
> +multiboot "module". For example:
> +
> +.. parsed-literal::
> +
> +  |qemu_system| --accel kvm,xen-version=0x40011,kernel-irqchip=split \\
> +       -chardev stdio,id=char0 -device xen-console,chardev=char0 \\
> +       -display none  -m 1G  -kernel xen -initrd bzImage \\
> +       -append "pv-shim console=xen,pv -- console=hvc0 root=/dev/xvda1" \\
> +       -drive file=${GUEST_IMAGE},if=xen

Is the space between -- and console= intentionsl?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.
Virtualization:  qemu.org | libguestfs.org