Vasudha Ramnath <[EMAIL PROTECTED]> writes:
>
> I'm running FreeBSD 3.1-RELEASE.
>
> Could someone explain what the poll() function in a device driver should
> do ?
>
> Can it return POLLERR or POLLHUP ?
>
> I have a test driver that returns these values from the poll() function.
> However, the application
> that called the select() is not getting an error. Instead, the select
> is returning that the particular file descriptor is, in this case,
> 'readable' !
Take a look at "selscan" algorithm in /usr/src/sys/kern/sys_generic.c
if you wish to learn more.
Basically, if your driver doesn't implement the poll() functionality,
it can always return 0. This will ensure that select never wakes up
because of a file descriptor associated with your driver.
-Arun
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