[libvirt] [Xen-devel] [PATCH] libxl: detect support for save and restore
Jim Fehlig
jfehlig at suse.com
Thu Jun 26 00:14:56 UTC 2014
Eric Blake wrote:
> On 06/25/2014 12:13 PM, Jim Fehlig wrote:
>
>> libxl does not support save, restore, or migrate on all architectures,
>> notably ARM. Detect whether libxl supports these operations using
>> LIBXL_HAVE_NO_SUSPEND_RESUME. If not supported, drop advertisement of
>> <migration_features>.
>>
>> Found by Ian Campbell while improving Xen's OSSTEST infrastructure
>>
>> http://lists.xen.org/archives/html/xen-devel/2014-06/msg02171.html
>> Signed-off-by: Jim Fehlig <jfehlig at suse.com>
>> ---
>>
>> Derived from a test patch I sent to Ian Campbell
>>
>> http://lists.xen.org/archives/html/xen-devel/2014-06/msg03150.html
>>
>> Includes fixups Ian provided later in the thread.
>>
>> src/libxl/libxl_conf.c | 4 ++++
>> src/libxl/libxl_driver.c | 8 ++++++++
>> 2 files changed, 12 insertions(+)
>>
>
>
>>
>> +#ifndef LIBXL_HAVE_NO_SUSPEND_RESUME
>>
>
> Double negative logic is hard to read. Oh well.
>
>
>
>>
>> static virDriver libxlDriver = {
>> @@ -4594,10 +4598,12 @@ static virDriver libxlDriver = {
>> .domainSetMemoryFlags = libxlDomainSetMemoryFlags, /* 0.9.0 */
>> .domainGetInfo = libxlDomainGetInfo, /* 0.9.0 */
>> .domainGetState = libxlDomainGetState, /* 0.9.2 */
>> +#ifndef LIBXL_HAVE_NO_SUSPEND_RESUME
>> .domainSave = libxlDomainSave, /* 0.9.2 */
>> .domainSaveFlags = libxlDomainSaveFlags, /* 0.9.4 */
>> .domainRestore = libxlDomainRestore, /* 0.9.2 */
>> .domainRestoreFlags = libxlDomainRestoreFlags, /* 0.9.4 */
>> +#endif
>>
>
> Hmm - do we do conditional registration in any other driver based on
> configure-time results? I'd almost rather always provide the driver
> registration, and then use #ifdefs in the body of that function to
> either provide a sane result or else report that the compilation
> environment was too old, rather than omit the support altogether.
I sent a V2 which takes your preferred approach
https://www.redhat.com/archives/libvir-list/2014-June/msg01305.html
> Maybe get Dan's opinion on this?
>
Ok. I lean towards V2 since it avoids the double negative.
Regards,
Jim
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