Asynchronous I/O on UNIX?

[William L. Sebok]

In article <604 at unisoft.UUCP> paul at unisoft.UUCP (n) writes:
>	The major problem in implementation under Unix is the concept of IO
>context, with Unix an IO's context (u_base, u_count, u_offset) are in a
>processes 'udot' if you are going to be doing multiple IO's you need to be
>able to send this information to the device with the queued IO (you also have
>to send the process ID, the completion routine's virtual address and the
>parameter you are going to give to the completion routine).

I noticed that in the transition from the 4.1 BSD to the 4.2 BSD kernel,
references in the i/o drivers to u.u_base, u.u_count, u.u_offset are replaced
by references to members of a uio structure.  This was the only change (that I
remember) that I had to make in some locally written drivers I ported.  I
wondered and still wonder if this change means that support of asynchronous
i/o is in the works in BSD.
-- 
Bill Sebok			Princeton University, Astrophysics
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