Date: Thu, 26 May 2005 20:36:21 -0400 From: Aziz Kezzou <french.linuxian@gmail.com> To: 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: <3727392705052617366706577c@mail.gmail.com> In-Reply-To: <4296410C.1020108@chiaro.com> References: <3727392705052613381067f2a2@mail.gmail.com> <4296410C.1020108@chiaro.com>
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> > 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; }
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