Re: [libvirt] [PATCH v2 0/8] libxl: PVHv2 support

On 9/18/18 6:50 PM, Marek Marczykowski-Górecki wrote: > This is a respin of my old PVHv1 patch[1], converted to PVHv2. > Should the code use "PVH" name (as libxl does internally), or "PVHv2" as in > many places in Xen documentation? I've chosen the former, but want to confirm > it. From libvirt's perspective it should be "PVH". If anything, the Xen documentation should change. AFAIK the various PVH attempts/names (PVHv1, hvmlite, PVHv2, ...) have merged to simply be known as "PVH". > > Also, not sure about VIR_DOMAIN_OSTYPE_XENPVH (as discussed on PVHv1 patch) - > while it will be messy in many cases, there is > libxl_domain_build_info.u.{hvm,pv,pvh} which would be good to not mess up. > Also, PVHv2 needs different kernel features than PV (CONFIG_XEN_PVH vs > CONFIG_XEN_PV), so keeping the same VIR_DOMAIN_OSTYPE_XEN could be > confusing. > On the other hand, libxl_domain_build_info.u.pv is used in very few places (one > section of libxlMakeDomBuildInfo), so guarding u.hvm access with > VIR_DOMAIN_OSTYPE_HVM may be enough. > For now I've reused VIR_DOMAIN_OSTYPE_XEN - in the driver itself, most of > the code is the same as for PV. I should have read your v1 cover letter closer and agreed on the approach before spending time looking at code :-). But in the end I still think the OS type is VIR_DOMAIN_OSTYPE_XEN with the machine attribute specifying PV vs PVH. I use the fact that both OS types are modified to run on Xen to rationalize using VIR_DOMAIN_OSTYPE_XEN for both. Perhaps it would be best for a third opinion and Daniel (cc'd) can chime in. > Since PVHv2 relies on features in newer Xen versions, I needed to convert also > some older code. For example b_info->u.hvm.nested_hvm was deprecated in favor > of b_info->nested_hvm. While the code do handle both old and new versions > (obviously refusing PVHv2 if Xen is too old), this isn't the case for tests. > How it should be handled, if at all? Due to the compilation error in patch 5, I haven't checked patches 6-8 on xen < 4.9, which may help me understand the problem you describe. Sorry it is not obvious to me from the reading.