Re: [Xen-devel] PCI passthrough for HVM with stubdomain broken by "tools/libxl: handle the iomem parameter with the memory_mapping hcall"

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.06.16 at 11:44, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 23/06/16 09:32, Jan Beulich wrote:
>> I wonder what good the duplication of the returned domain ID does: I'm
>> tempted to remove the one in the command-specific structure. Does
>> anyone have insight into why it was done that way?
> 
> This hypercall, and its sibling XEN_SYSCTL_getdomaininfolist have crazy
> semantics, which go out of their way to make it easy to get wrong.
> 
> It is important that you always check the returned domid, as it may not
> be the domain you asked for.  In particular, if a domain you are looking
> after dies, the adjacent domain's information will be returnned.

Same question as to Marek: How is this related to my remark?

> Also, noone has yet addressed the issue that, strictly speaking,
> xen_domctl_getdomaininfo_t is versioned by both the DOMCTL and the
> SYSCTL interface version.  This in particular makes things interesting
> for valgrind support.

True, and afaict also the case for XEN_SCHEDULER_*. No idea how
to cleanly address this other than by folding the two versions.

Jan


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