cvs commit: src/sys/dev/io iodev.c

Peter Jeremy peterjeremy at
Sat Aug 9 00:13:03 UTC 2008

On 2008-Aug-08 12:26:31 -0400, John Baldwin <jhb at> wrote:
>It should be setting D_TRACKCLOSE though so that close() reliably clears the 
>flag even in single-threaded processes.  You can still get odd behavior if 
>you explicitly open it twice in an app and then close one of the two fd's.  
>You will no longer have IO permission even though you still have one fd open.  
>However, if you do that I think you deserve what you asked for. :)

That behaviour may be legitimate:  Your code links with libraries foo and
bar that each independently open /dev/io so they can frob different things
in IO space.  libfoo needs ongoing access to device foo and so keeps its
descriptor open.  libbar only needs once-off access to device bar and so
closes /dev/io once it's finished its initialisation.  Libraries foo and
bar are completely independent and shouldn't need to know anything about
each other and your app shouldn't need to know that libraries it's using
frob around in IO space.

Peter Jeremy
Please excuse any delays as the result of my ISP's inability to implement
an MTA that is either RFC2821-compliant or matches their claimed behaviour.
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