Re: [dpdk-dev] [PATCH v2] eal: sPAPR IOMMU support in pci probing for vfio-pci in ppc64le

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

Hi Gowrishankar,

> Hi Anatoly,
> 
> 
> On Friday 03 March 2017 02:38 PM, Burakov, Anatoly wrote:
> >
> > Please correct me if I'm wrong here, but wouldn't all of these
> > SPAPR-specific defines and structures not be available for pre-4.2? So
> > the kernel check should also contain all the definitions and structs
> > as well. Maybe it's better to just not compile SPAPR support on older
> kernels, rather than duplicating all the VFIO code.
> >
> > Any opinions?
> >
> >
> Thanks for this check.
> 
> As far as its trace in linux main stream, I see it was merged in 4.2.
> But, it depends on distro when we go back in older kernels.
> Some distros may have back-ported it too - eg. linux-3.10.0-514.6.2.el7 in
> RHEL 7.2 supports it. So, we might realise whether not supported, only in run
> time (atleast without autoconf sort of stuff in dpdk) IMO.
> any thoughts ?.
> 
> Regards,
> Gowrishankar

I guess the best way to go would be something like:

#ifndef SPAPR_IOMMU_TYPE
#define RTE_SPAPR_IOMMU 6
#define SPAPR_MAP_FOO bar
struct spapr_foo {};
struct spapr_bar {};
#else
#define RTE_SPAPR_IOMMU SPAPR_IOMMU_TYPE
#endif

Even though it's a bit messy, this way we won't be dependent on kernel version or if any distro has backported SPAPR support. Does that sound reasonable?

Thanks,
Anatoly