Re: [Xen-devel] [RFC] Disable xen platform device when it is not needed.

[Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>]

Thank all for the comments.

I will create the patch to add "xen_platform_pci" option in guest
config file to disable xen platform device.

    xen_platform_pci=0: Disable xen platform device.
    xen_platform_pci=1: Enable xen platform device. (default)

Thanks,
--
Yuji Shimada

On Wed, 18 Feb 2009 09:15:43 +0900
Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx> wrote:

> I plan to create the patch to disable xen platform device when it
> is not needed. Please let me know if anyone has a comment.
> 
> Windows guest shows xen platform device as unknown
> device with "!" mark in the device manager, when PV drivers are not
> loaded. So I'd like to disable xen platform device.
> 
> If following conditions are all true, I will disable xen platform
> device. Otherwise, xen platform device will be enabled.
> 
>     - All entries in "disk" parameter have "ioemu:" prefix in DEV field.
>         Example:
>         disk = [ '/var/images/guest.img,ioemu:hda,w', ',ioemu:hdc:cdrom,r' ]
> 
>     - All entries in "vif" parameter have "type=ioemu".
>         Example:
>         vif = [ 'type=ioemu, bridge=eth0', 'type=ioemu, bridge=eth1' ]
> 
>     - "vscsi" parameter is not specified.
> 
> Xen platform device has functions for PV drivers and guest
> firmware (hvmloader and rombios). The functions for PV drivers will be
> disabled when xen platform device is disabled. This is no problem. But
> the function for guest firmware should not be disabled.
> 
> I will move the function for guest firmware from xen platform device
> to host bridge. The interface between host bridge and guest firmware
> will be in PCI configuration space, because host bridge does not have
> io resource and memory resource.
> 
> The function which I will move is switching RW/RO state of ROM memory
> area. Please refer
> qemu-xen/hw/xen_platform.c:xen_platform_ioport_writeb. I will not move
> the other functions.
> 
> Thanks,
> --
> Yuji Shimada

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