Date: Fri, 31 Mar 2006 15:37:24 -0500 From: John Baldwin <jhb@freebsd.org> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: Perforce Change Reviews <perforce@freebsd.org> Subject: Re: PERFORCE change 94334 for review Message-ID: <200603311537.26612.jhb@freebsd.org> In-Reply-To: <F2830856-3349-4EA5-B7FC-C927950FE741@xcllnt.net> References: <200603302348.k2UNmDJd096792@repoman.freebsd.org> <200603310851.42196.jhb@freebsd.org> <F2830856-3349-4EA5-B7FC-C927950FE741@xcllnt.net>
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On Friday 31 March 2006 12:37, Marcel Moolenaar wrote: > > On Mar 31, 2006, at 5:51 AM, John Baldwin wrote: > > > On Thursday 30 March 2006 06:48 pm, Marcel Moolenaar wrote: > >> http://perforce.freebsd.org/chv.cgi?CH=94334 > >> > >> Change 94334 by marcel@marcel_nfs on 2006/03/30 23:47:36 > >> > >> Strip-down puc(4): > >> o Remove PUC_PORT_TYPE_UART: we always use uart(4) now, so we > >> can use PUC_PORT_TYPE_COM for that. > >> o Remove PUC_PORT_UART_*: we don't support UART sub-types. All > >> UARTs are standard ns8250 again. > >> o Remove PUC_FLAGS_MEMORY and PUC_FLAGS_ALTRES: we try I/O ports > >> first and if that fails, we try memory. > >> o Remove PUC_FASTINTR: we try setting up a fast handler first, > >> and if that fails we try a MPSAFE one. > > > > Unfortunately that algorithm doesn't work in the case of a shared > > interrupt > > if puc is the first device to attach. The other devices then just > > "lose". > > It's the standard algorithm I use. I expect the platform to either > share a fast interrupt handler with a non-fast handler or silently > downgrade my fast handler to a mpsafe one if later events demand > this. All I can indicate in my driver is what I'm capable of. The > MD interrupt code should do what needs to be done based on that > and the surrounding environment and subsequent events. I have no > visibility over and/or knowledge about that and cannot program > for it then. None of the platforms have ever done the downgrade thing FWIW. Only ppc doesn't share INTR_FAST now, so I think you could probably just always use INTR_FAST. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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