Re: [PATCH v3 23/24] libxl: Add support for non-PCI passthrough

[Ian Campbell <ian.campbell@citrix.com>]

On Thu, 2015-01-29 at 13:51 +0000, Julien Grall wrote:
> On 29/01/15 12:31, Stefano Stabellini wrote:
> > On Thu, 29 Jan 2015, Julien Grall wrote:
> >> Hi Stefano,
> >>
> >> On 29/01/15 11:12, Stefano Stabellini wrote:
> >>>> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> >>>> index 029d2e2..b7ef528 100644
> >>>> --- a/tools/libxl/libxl_create.c
> >>>> +++ b/tools/libxl/libxl_create.c
> >>>> @@ -1430,6 +1430,16 @@ static void domcreate_attach_pci(libxl__egc *egc, libxl__multidev *multidev,
> >>>
> >>> I think you should at least rename domcreate_attach_pci to something
> >>> more generic, like domcreate_attach_dev.
> >>
> >> Actually I was planning to add a domcreate_attach_dtdev but I forgot
> >> about it.
> >>
> >> What the best approach for this?
> > 
> > Either one would work. But don't add non-PCI passthrough code to a
> > function named domcreate_attach_pci :-)
> 
> Right, it was a quick & dirty implementation which I forgot to clean up.
> 
> >>>
> >>>>          }
> >>>>      }
> >>>>  
> >>>> +    for (i = 0; i < d_config->num_dtdevs; i++) {
> >>>> +
> >>>> +        ret = libxl__device_dt_add(gc, domid, &d_config->dtdevs[i]);
> >>>> +        if (ret < 0) {
> >>>> +            LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
> >>>> +                       "libxl__device_dt_add failed: %d\n", ret);
> >>>> +            goto error_out;
> >>>> +        }
> >>>> +    }
> >>>
> >>> You are allowed to call xc_* functions from here. The
> >>> libxl__device_dt_add wrapper doesn't add much value.
> >>
> >> I would like to keep the wrapper. It's in sync with the PCI solution and
> >> it will avoid refactoring later for add new code.
> > 
> > But in the PCI case there is a lot of code in the function.
> > Regardless if you think it is useful, keep it.
> 
> If we plan to implement a proper platform device pass-through we will
> have to add lots of code.
> 
> Wei, Ian & Ian, do you have any opinions?

A new function (e.g. domcreate_attach_dtdev) between
domcreate_attach_pci and domcreate_console_available in the callback
chain is the right answer, I think.

Unless there is a lot more code to come then I'm not sure adding
libxl_dtdev.c or the function in there is necessary -- just call
xc_assign... from the new domcreate_attach function. It's up to you
though.

Ian.