Date: Tue, 19 Apr 2016 15:42:40 +0000 From: Howard Su <howard0su@gmail.com> To: John Baldwin <jhb@freebsd.org>, freebsd-current@freebsd.org Subject: Re: Mis-use of BUS_PASS_ORDER_MIDDLE Message-ID: <CAAvnz_oDM83miGcX_Qh0Rc2f8o=s_hkSiuPkwEacngpxhZS=Ew@mail.gmail.com> In-Reply-To: <1611132.EbTME86UTe@ralph.baldwin.cx> References: <CAAvnz_rmbgM9t47eqV91ASXHddJjMyEucpF4_f-3Ed5pNoM8Bw@mail.gmail.com> <1611132.EbTME86UTe@ralph.baldwin.cx>
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On Tue, Apr 19, 2016 at 2:53 AM John Baldwin <jhb@freebsd.org> wrote: > On Monday, April 18, 2016 11:10:12 PM Howard Su wrote: > > I noticed several places there are code like this, especially in some a= rm > > low level drivers. > > EARLY_DRIVER_MODULE(aw_ccu, simplebus, aw_ccu_driver, aw_ccu_devclass, > > 0, 0, BUS_PASS_BUS + BUS_PASS_ORDER_MIDDLE); > > > > =E2=80=8BI feel the usage of BUS_PASS_ORDER_MIDDLE is misused. There ar= e another > > macro EARLY_DRIVER_MODULE_ORDERED, which take an additional parameter > > "order". I believe BUS_PASS_ORDER_xxx is used for that parameter. > > No, this is actually correct. The _ORDERED variants actually accept a > SI_ORDER_* value to determine how drivers contained in a single .ko file > are registered (in particular if you have several drivers in a .ko file > you typically want the "top-most" driver to attach last so that all the > other drivers are ready once the actual device is attached). > Why not use _ORDERED here to achieve same thing? _ORDERED(...., SI_ORDER_LAST, BUS_PASS_BUS)? I am thinking to add some macro like BUS_DRIVER_MODULE, INT_DRIVER_MODULE, TIMER_DRIVER_MODULE, so that the driver can declare itself in such way. If we can avoid usage of BUS_PASS_ORDER_XXX, the macro is much cleaner. I am plan to do is: in autoconf phase, first load timer, int and some bus, etc low level drivers first, then set cold=3D0, then load other driver to work around the problem that driver needs special handling on cold which is not necessary. of course, this may depends on your change of ap_startup. thoughts? > -- > John Baldwin > --=20 -Howard
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