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Date:Sat, 10 Apr 2004 14:18:10 +0100 
Subject:sys_async_io and pipes under linux 
From:Joe Wood 
Volume-ID: 

Hi,

The procedure sys_async_io, (see ref sysio) takes a devices and establishes
an asynchronious reader/writer routine. Ultimately this is a call to fcntl
(2) in the kernel.

Now the following 2 fragments return successfully:

    sysopen ( '/dev/tty', 0, false ) -> pin ;
    read -> sys_async_io ( pin, 0 ) ;

and

    sys_socket ( `U`, `D`, false ) -> pin ;
    read -> sys_async_io ( pin, 0 ) ;


But
    syspipe (false) -> pin -> pout ;             ;;; order may be wrong
here, but _that_ is not the problem
    read -> sys_async_io ( pin, 0 ) ;

fails inside the kernel, ENOTTY. I know this is coming from the kernel
because I ran strace to see the system calls.

Does anybody know the reason.

Thanks
Joe