Re: [Xen-devel] [PATCH v3 1/7] xen-pciback: Document the various parameters and attributes in SysFS

David Vrabel
2014-07-09T12:17:10Z

On 08/07/14 19:58, konrad@kernel.org wrote:
> From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>
> Which hadn't been done with the initial commit.
[...]
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-driver-pciback
> @@ -0,0 +1,84 @@
> +What: /sys//module/xen_pciback/parameters/verbose_request

It's my understanding that module parameters are not typically part of
the ABI.

> +What: /sys/module/xen_pciback/parameters/permissive
> +Date: Oct 2011
> +KernelVersion: 3.1
> +Contact: xen-devel@lists.xenproject.org
> +Description:
> + Allow non-emulated (raw) access to PCI configuration space by
> + the guest frontend. This can have adverse affect as the guest
> + can destabilize the initial domain.

WTF? Why does it even have such an unsafe option?

> +What: /sys/bus/pci/drivers/pciback/irq_handlers
> +Date: Oct 2011
> +KernelVersion: 3.1
> +Contact: xen-devel@lists.xenproject.org
> +Description:
> + A list of all of the PCI devices owned by Xen PCI back and
> + whether Xen PCI backend will acknowledge the interrupts received
> + and the amount of interrupts received. Xen PCI back acknowledges
> + said interrupts only when they are level, shared with another
> + guest, and enabled by the guest.

This should be a device property or something in debugfs.

> +What: /sys/bus/pci/drivers/pciback/irq_handler_state
> +Date: Oct 2011
> +KernelVersion: 3.1
> +Contact: xen-devel@lists.xenproject.org
> +Description:
> + An option to toggle Xen PCI back to acknowledge (or stop)
> + interrupts for the specific device regardless of whether the
> + device is shared, enabled, or on a level interrupt line.
> + Writing a string of DDDD:BB:DD.F will toggle the state.
> + This is Domain:Bus:Device.Function where domain is optional.

I do not understand under what circumstances this should be used in.

David