Date: Mon, 9 Jul 2012 01:17:52 -0400 From: Arnaud Lacombe <lacombar@gmail.com> To: Warner Losh <imp@bsdimp.com> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: newbus' ivar's limitation.. Message-ID: <CACqU3MVVDSo8fNmCcCm0dyq6skOf%2BJ_9bUWmxpBi137FD=efyg@mail.gmail.com> In-Reply-To: <8048FFC5-6952-49FC-849D-EA1A5675ACBE@bsdimp.com> References: <CACqU3MVh6shncm2Vtqj9oe_HxowWscCZ1eJf0q2F%2B=t_xKKBfQ@mail.gmail.com> <31A0DCE7-3B93-41BC-805A-E0B163892112@bsdimp.com> <CACqU3MVy65ck%2Bb8TKXwfXnBV9iuFzj%2ButRBH4Ecg6XDz3Vg5kQ@mail.gmail.com> <5C18109D-E7A8-4868-BEA9-26B63360BB24@bsdimp.com> <CACqU3MUcbozpyqRLUS91p-%2BXANsisLoHzYpbQ8KjCr02=kMHYg@mail.gmail.com> <8048FFC5-6952-49FC-849D-EA1A5675ACBE@bsdimp.com>
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Hi, On Mon, Jul 9, 2012 at 12:37 AM, Warner Losh <imp@bsdimp.com> wrote: > > On Jul 8, 2012, at 9:46 PM, Arnaud Lacombe wrote: > >> On Sun, Jul 8, 2012 at 11:31 PM, Warner Losh <imp@bsdimp.com> wrote: >>> >>> On Jul 8, 2012, at 9:26 PM, Arnaud Lacombe wrote: >>> >>>> Hi, >>>> >>>> On Sun, Jul 8, 2012 at 10:07 PM, Warner Losh <imp@bsdimp.com> wrote: >>>>> >>>>> On Jul 8, 2012, at 7:22 PM, Arnaud Lacombe wrote: >>>>>> Ok, yet another Newbus' limitation. Assuming a device exports more >>>>>> than one interface, and one of its child has need to use more than o= ne >>>>>> interface, each interfaces cannot register, concurrently, its own >>>>>> ivar. While I try to always have a single child per >>>>>> interface/resource, I need to keep some compatibility with the old w= ay >>>>>> of doing thing (POLA wrt. drivers I cannot/will not convert and >>>>>> userland). So, it would have been nice if ivar had been per-interfac= e, >>>>>> not global and unique to one device. >>>>> >>>>> There's one pointer for the ivars. The bus code gets to determine wh= at the ivar looks like, because the interface is totally private to the bus= . So long as it returns the right thing for any key that's presented, it d= oesn't matter quite how things are done. >>>>> >>>>> So I'm not sure I understand what you are saying here. >>>>> >>>> dev0 implements two interfaces: A and B. dev1, child of dev0, needs to >>>> use both interfaces. There is no generic way for dev0 to export >>>> independent ivars for both interface. For now, I restricted the >>>> function of the second interface not to need ivar, but that's kind of >>>> hackish. >>> >>> Only if the IVARs for interface A and interface B have overlapping valu= es. If the Ivar keys don't overlap, then there's no problems at all. Cert= ainly less hackish than not using them at all. Since dev0 knows the layout= of the ivar that it set on its child, this presents no problems at all. I= t would return the values from A from the right part of the ivar, and those= from B in the right part. Apart from the coordination of Ivar numbers, as= I outlined in my last post, there's no issue here. >>> >> I think we should not be talking about the same API here. I have no >> idea what you mean by "the key to value translation", nor "Ivar >> numbers". What I refer to is that device_set_ivars() / >> device_get_ivars() acts on a single instance variables from `struct >> device': `ivars'. In that case, I do not really see how to set that >> specific field to two distinct values for each interfaces. > > We are talking about the ivar interface. You are just misunderstanding h= ow it is used. > yes I indeed did... silly, silly me :-) - Arnaud
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