Re: [PATCH 7/9] kvm tools: Use dynamic IO port allocation in virtio-console driver

[Ingo Molnar <mingo@elte.hu>]

* Sasha Levin <levinsasha928@gmail.com> wrote:

>  void virtio_console__init(struct kvm *kvm)
>  {
>  	u8 dev, line, pin;
> +	u16 console_base_addr;
>  
>  	if (irq__register_device(VIRTIO_ID_CONSOLE, &dev, &pin, &line) < 0)
>  		return;
>  
>  	virtio_console_pci_device.irq_pin	= pin;
>  	virtio_console_pci_device.irq_line	= line;
> +	console_base_addr			= ioport__find_free_range();
> +	virtio_console_pci_device.bar[0]	= console_base_addr | PCI_BASE_ADDRESS_SPACE_IO;
> +	cdev.base_addr				= console_base_addr;
>  	pci__register(&virtio_console_pci_device, dev);
> -	ioport__register(IOPORT_VIRTIO_CONSOLE, &virtio_console_io_ops, IOPORT_VIRTIO_CONSOLE_SIZE);
> +	ioport__register(console_base_addr, &virtio_console_io_ops, IOPORT_SIZE);

Why is the ioport registration done in two steps?

Wouldnt a better sequence be something like:

> +	console_base_addr			= ioport__register(&virtio_console_io_ops, IOPORT_SIZE);
>
> +	virtio_console_pci_device.bar[0]	= console_base_addr | PCI_BASE_ADDRESS_SPACE_IO;
> +	cdev.base_addr				= console_base_addr;
>  	pci__register(&virtio_console_pci_device, dev);

I.e. first register the ioport range - this would also get a free 
range for you, and then register the PCI driver?

Or something even more compact could be done i suspect - all of the 
drivers seem to be using the same registration sequence.

Thanks,

	Ingo