Date: Wed, 11 Jul 2012 23:20:09 -0600 From: Warner Losh <imp@bsdimp.com> To: Arnaud Lacombe <lacombar@gmail.com> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: newbus' ivar's limitation.. Message-ID: <73F3FBC9-337C-4F61-9470-5173D6DAE56B@bsdimp.com> In-Reply-To: <CACqU3MVZmuavxcLZ8LGqP5Ze0yW4bkd5NfSFUfUK_Q6wbzDs8Q@mail.gmail.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> <CACqU3MVVDSo8fNmCcCm0dyq6skOf%2BJ_9bUWmxpBi137FD=efyg@mail.gmail.com> <CACqU3MVZmuavxcLZ8LGqP5Ze0yW4bkd5NfSFUfUK_Q6wbzDs8Q@mail.gmail.com>
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On Jul 11, 2012, at 9:47 PM, Arnaud Lacombe wrote: > Hi, >=20 > On Mon, Jul 9, 2012 at 1:17 AM, Arnaud Lacombe <lacombar@gmail.com> = wrote: >> Hi, >>=20 >> On Mon, Jul 9, 2012 at 12:37 AM, Warner Losh <imp@bsdimp.com> wrote: >>>=20 >>> On Jul 8, 2012, at 9:46 PM, Arnaud Lacombe wrote: >>>=20 >>>> On Sun, Jul 8, 2012 at 11:31 PM, Warner Losh <imp@bsdimp.com> = wrote: >>>>>=20 >>>>> On Jul 8, 2012, at 9:26 PM, Arnaud Lacombe wrote: >>>>>=20 >>>>>> Hi, >>>>>>=20 >>>>>> On Sun, Jul 8, 2012 at 10:07 PM, Warner Losh <imp@bsdimp.com> = wrote: >>>>>>>=20 >>>>>>> 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 one >>>>>>>> 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 way >>>>>>>> of doing thing (POLA wrt. drivers I cannot/will not convert and >>>>>>>> userland). So, it would have been nice if ivar had been = per-interface, >>>>>>>> not global and unique to one device. >>>>>>>=20 >>>>>>> There's one pointer for the ivars. The bus code gets to = determine what 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 doesn't matter quite how things are done. >>>>>>>=20 >>>>>>> So I'm not sure I understand what you are saying here. >>>>>>>=20 >>>>>> 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. >>>>>=20 >>>>> Only if the IVARs for interface A and interface B have overlapping = values. If the Ivar keys don't overlap, then there's no problems at = all. Certainly 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. It 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. >>>>>=20 >>>> 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. >>>=20 >>> We are talking about the ivar interface. You are just = misunderstanding how it is used. >>>=20 >> yes I indeed did... silly, silly me :-) >>=20 > Actually, no. I wasn't that silly, neither was I misunderstanding > anything beside how *you* wanted it to be used, which is, I sorry to > say, unacceptable. The last thing I want is to pollute an interface > with a single-purpose, hand-crafted, bus. I was to just throw away all > that ivar stuff and go into hinted child configuration for now, > waiting for FDT... but of course, I figured out after a few hours that > hinted child attachment requires `bus_hinted_child' to be set in the > parent, as does bus_enumerate_hinted_children() / bus_generic_attach() > to explicitly pollute my code. All this stuff should be done > implicitly to support N:1 interfaces/client relationship. N > *independent* interfaces being provided by a single driver; of course, > I'm not even going back to require those interface being provided by > multiple drivers, it is already a dead end. >=20 > I am not even sure any driver in the tree provides more than one = interface... >=20 > For whatever reason, I am more and more thinking that this all > new-bus[0] stuff is *way* overkill, static, bloated at will, and > missing critical features; a huge PITA to use, for the intended > purpose. >=20 > /me pissed. >=20 > - Arnaud >=20 > [0]: damn, why is it even called "newbus", this stuff is 14 years old. > It really belongs to a museum, not production code... I'm sorry you feel that way. Honestly, though, I think you'll be more pissed when you find out that = the N:1 interface that you want is being done in the wrong domain. But = I've been wrong before and look forward to seeing your replacement. acpi_pcib_acpi.c, btw, implements both PCIB interfaces and ACPI = interfaces. Warner=
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