RE: [Xen-devel] passing hypercall parameters by pointer

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Hollis Blanchard
>Sent: Thursday, August 18, 2005 6:11 AM
>
>I have no answer for parameters that are very large, but I wonder how
many
>cases there are. For example, DOM0_READCONSOLE could just be limited
>to 4KB
>reads, and if there's more data than that, call it again. Perhaps there
is
>some case-specific solution to xc_get_pfn_list() as well.
>

If one hypercall wants to get specific context at one point atomically,
"call it again" several times actually returns mixed contexts belonging
to different time points. That's not desired. Even if people want to add
atomic protection for such type of case, performance will be affected a
lot and more risk to suffer dead-lock.

Thanks,
Kevin

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