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Re: [Xen-devel] [Question] Proper location for Linux error code (-EPROBE_DEFER) in Xen

On 01.08.19 17:31, Oleksandr wrote:


Hi, Roger

I think it would help if you describe why such error code is needed by
Xen and how it would be used.

 This is needed for the upcoming V2 of the IPMMU driver (ARM) [1] which may request  deferred probing (returns -EPROBE_DEFER) depending on what device will be probed the first
 (Root device must be registered before Cache devices. If not the case,
 driver will deny further Cache device probes until Root device is registered).

As we can't guarantee a fixed pre-defined order for the device nodes in DT, we need to be ready for the situation where devices being probed in "any" order. So, framework (drivers/passthrough/arm/iommu.c) will be modified a bit to be able to handle -EPROBE_DEFER returning by driver.

[1] https://lists.xenproject.org/archives/html/xen-devel/2017-07/msg02679.html

Sorry, I provided wrong link.

The correct link should be:



Oleksandr Tyshchenko

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