Re: [libvirt] [Xen-devel] [PATCH] libxl: detect support for save and restore

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(a)suse.com&gt; > --- > > 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.

Maybe get Dan's opinion on this?