Date: Fri, 27 May 2005 16:43:23 -0700 From: Pete Heerboth <pheerboth@apple.com> To: Aziz Kezzou <french.linuxian@gmail.com> Cc: dave baukus <dbaukus@chiaro.com>, freebsd-hackers <freebsd-hackers@freebsd.org>, freebsd-net <freebsd-net@freebsd.org> Subject: Re: Pseudo-device driver & select ?? Message-ID: <AB7681FC-5AC2-41A0-941D-FBABC70D0E11@apple.com> In-Reply-To: <37273927050526180026d23c7d@mail.gmail.com> References: <3727392705052613381067f2a2@mail.gmail.com> <4296410C.1020108@chiaro.com> <3727392705052617366706577c@mail.gmail.com> <37273927050526180026d23c7d@mail.gmail.com>
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You might want to take a look at the bpf pseudo device and how it handles polls int bpf.c. You need to use the selrecord() and selwakeup() functions. Check out: http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/net/ On May 26, 2005, at 6:00 PM, Aziz Kezzou wrote: >>> >>> Aziz Kezzou wrote: >>> >>>> Hi all, >>>> I am trying to implement a small kld pseudo-device driver on >>>> FreeBSD 5.3 that >>>> behaves just like a socket with regards to the select system call. >>>> >>>> Currently, I am using the sample echo pseudo-device driver from >>>> http://www.freebsd.org/doc/en_US.ISO8859-1/books/arch-handbook/ >>>> driverbasics-char.html >>>> as an example. However, whenever I call select on the file >>>> descriptor of "/dev/echo" it always returns even when there is >>>> no data >>>> to be read. >>>> >>>> I looked at the socket code and it looks like I need to provide >>>> my own >>>> "fo_select" function in the fileops data structure. Am i right ? >>>> How >>>> do I do that ? The sample echo pseudo-device driver above uses >>>> "struct cdevsw" instead... >>>> >>>> Thanks >>>> -aziz >>>> _______________________________________________ >>>> freebsd-net@freebsd.org mailing list >>>> http://lists.freebsd.org/mailman/listinfo/freebsd-net >>>> To unsubscribe, send any mail to "freebsd-net- >>>> unsubscribe@freebsd.org" >>>> >>>> >>>> >>> look at spec_poll() >>> I beleive that when your device is opened the fileops{} will >>> point to the spec ops and you're code will be entered via >>> spec_poll() - now you just need to implement the poll/select notion >>> for your device. >>> >>> >> >> Thanks, >> Actually, il turned out to be very simple. >> I needed only to provide a "d_poll" function as part of the structure >> cdevsw, as follows : >> >> /* Character device entry points */ >> static struct cdevsw echo_cdevsw = { >> .d_version = D_VERSION, >> .d_open = echo_open, >> .d_close = echo_close, >> .d_read = echo_read, >> .d_write = echo_write, >> .d_poll = echo_poll, >> .d_name = "echo", >> }; >> >> with echo_poll : >> static int >> echo_poll(struct cdev *dev, int events, struct thread *td) >> { >> >> uprintf( "echo_poll called : data_available = %d!\n", >> data_available ); >> if(data_available == 0) >> return 0; >> data_available = 0; >> return 1; >> } >> >> > > Now the question is, if I don't have any data available when select > (i.e d_poll ) is called, how do I notify select when data arrives ? > looks like "d_poll" is called only once (the name is a bit misleading > here ;-) , isn't it ? > > Any hints ? > Thanks. > -aziz > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >
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