On 25/10/2023 7:26 pm, David Woodhouse wrote:
> On Wed, 2023-10-25 at 13:20 -0500, Eric Blake wrote:
>> On Wed, Oct 25, 2023 at 03:50:42PM +0100, David Woodhouse wrote:
>>> +
>>> +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?
> Yes, that one is correct. The -- is how you separate Xen's command line
> (on the left) from the guest kernel command line (on the right).
To expand on this a bit.
Multiboot1 supports multiple modules but only a single command line. As
one of the modules passed to Xen is the dom0 kernel, we need some way to
pass it's command line, hence the " -- ".
Multiboot2 and PVH support a command line per module, which is the
preferred way to pass the commandlines, given a choice.
~Andrew
