> Am 10.09.2015 um 14:03 schrieb Thomas Huth <th...@redhat.com>: > >> On 10/09/15 12:40, David Gibson wrote: >>> On Thu, Sep 10, 2015 at 09:33:21AM +0200, Thomas Huth wrote: >>>> On 09/09/15 23:10, Thomas Huth wrote: >>>> On 08/09/15 07:15, David Gibson wrote: >>> ... >>>>> At this point rather than just implementing them as discrete machine >>>>> options, I suspect it will be more maintainable to split out the >>>>> h-random implementation as a pseudo-device with its own qdev and so >>>>> forth. We already do similarly for the RTAS time of day functions >>>>> (spapr-rtc). >>>> >>>> I gave that I try, but it does not work as expected. To be able to >>>> specify the options, I'd need to instantiate this device with the >>>> "-device" option, right? Something like: >>>> >>>> -device spapr-rng,backend=rng0,usekvm=0 >>>> >>>> Now this does not work when I use TYPE_SYS_BUS_DEVICE as parent class >>>> like it is done for spapr-rtc, since the user apparently can not plug >>>> device to this bus on machine spapr (you can also not plug an spapr-rtc >>>> device this way!). >>>> >>>> The spapr-vlan, spapr-vty, etc. devices are TYPE_VIO_SPAPR_DEVICE, so I >>>> also tried that instead, but then the rng device suddenly shows up under >>>> /vdevice in the device tree - that's also not what we want, I guess. >>> >>> I did some more tests, and I think I can get this working with one small >>> modification to spapr_vio.c > ... >>> i.e. when the dt_name has not been set, the device won't be added to the >>> /vdevice device tree node. If that's acceptable, I'll continue with this >>> approach. >> >> A bit hacky. >> >> I think it would be preferable to build it under SysBus by default, >> like spapr-rtc. Properties can be set on the device using -global (or >> -set, but -global is easier). > > If anyhow possible, I'd prefere to use "-device" for this instead, because > > a) it's easier to use for the user, for example you can simply use > "-device spapr-rng,?" to get the list of properties - this > does not seem to work with spapr-rtc (it has a "date" property > which does not show up in the help text?) > > b) unlike the rtc device which is always instantiated, the rng > device is rather optional, so it is IMHO more intuitive if > created via the -device option. > > So I'd like to give it a try with the TYPE_VIO_SPAPR_DEVICE first ... if > you then still don't like the patches at all, I can still rework them to > use TYPE_SYS_BUS_DEVICE instead.
Please don't use sysbus. If the vio device approach turns ugly, create a new spapr hcall bus instead. We should have had that from the beginning really. Alex
