Re: [Xen-devel] [v7][PATCH 13/16] libxl: construct e820 map with RDM information for HVM guest

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

> > > > > However long term I think it might make sense to try and reuse one of
> > > > > the existing libxl__arch hooks, i.e.
> > > > > libxl__arch_domain_init_hw_description or
> > > > > libxl__arch_domain_finalise_hw_description. On ARM these are to do with
> > > > > setting the Device Tree Blob, which included the memory map, so it is
> > > > > somewhat morally equivalent to configuring the e820 on x86, I think.
> > > > >
> > > > > Those hooks are only called from libxl__build_pv today, but calling them
> > > > > from libxl__build_hvm seems like it would be good too.
> > > > But seems this is raising some potential risks, isn't this? Although
> > > > libxl__arch_domain_init_hw_description() and
> > > > libxl__arch_domain_finalise_hw_description() are NOP to x86, they're
> > > > really working on ARM side. So if we call them inside
> > > > libxl__build_hvm(), any affects to ARM? I'm not very sure at this point
> > > > unless anyone can validate this change on ARM, or you really ensure my
> > > > concerns is unnecessary.
> > > All ARM guests use the PV code path so there is no risk.
> > Okay but please take a close look at this,
> >
> > libxl__build_pv(gc, domid, info, state)
> >       |
> >       + libxl__arch_domain_finalise_hw_description(libxl__gc *gc,
> >                                         libxl_domain_build_info *info,
> >                                         struct xc_dom_image *dom)
> >
> > But in our case we need this parameter, struct xc_hvm_build_args *args,
> > so how can we handle this conflict? Its not easy to add this, and it
> > doesn't make sense as well in pv case.
> This is an internal API, you can feel free to modify it as necessary.
I mean struct xc_hvm_build_args[] is a parameter specific to hvm so its 
wired to pass this in the case of hv. If we wrapper this again its not 
worth going this way.
> Please note that I started this subthread with "However long term I
> think it might make sense ...", This was not a request to redo this
> patch now.
Okay lets record this and now just keep moving forward with the original.

Thanks
Tiejun

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