Re: [Xen-devel] Regression building HVM domains following "x86: add bitmap of enabled emulated devices"

[Roger Pau Monnà <roger.pau@xxxxxxxxxx>]

El 11/11/15 a les 20.22, Andrew Cooper ha escrit:
> Actually CC-ing xen-devel this time.
> 
> On 11/11/15 19:13, Andrew Cooper wrote:
>> Hello,
>>
>> Xapi uses the Ocaml stub_xc_domain_create() which uses
>> xc_domain_create().  xc_domain_create() itself zeros the arch
>> configuration but passes flags straight through.
>>
>> As a result of c/s 171946ab "x86: add bitmap of enabled emulated
>> devices", xc_domain_create() can no longer be used to construct HVM
>> domains, failing the hypervisor-side sanity check.
>>
>> Needless to say, this has put a dent in XenServer's automated testing.
>>
>>
>> There are a couple of options, but neither of them are fantastic.
>>
>> 1) Have xc_domain_create() fill in XEN_X86_EMU_ALL based on
>> XEN_DOMCTL_CDF_hvm_guest and XEN_DOMCTL_CDF_pvh_guest
>>
>> or
>>
>> 2) Mandate that all callers provide a valid arch configuration,
>> essentially turning xc_domain_create() into xc_domain_create_config()
>>
>>
>> Longterm, what is the plan wrt guest construction?  With my x86
>> maintainership hat on, I don't want to keep XEN_DOMCTL_CDF_pvh_guest in
>> the interface, so I do not like 1) as an option.
>>
>> `git grep` indicates that the 3 users of xc_domain_create() are the
>> Ocaml/Python stubs and init-xenstore-domain.c which only constructs a PV
>> guest (which bypasses the issue), whereas libxl uses
>> xc_domain_create_config().  (For the python stubs, I expect this will
>> hit Oracle who are still using Xend to my knowledge).

Qemu upstream also uses xc_domain_create (see
hw/xenpv/xen_domainbuild.c:xen_domain_build_pv).

IMHO, I would just remove xc_domain_create and switch all users to
xc_domain_create_config. I can take care of this if it seems like the
best solution.

Roger.


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