RE: devfs + PCI serial card = no extra serial ports
Ed Vance (EdV@macrolink.com)
Fri, 14 Mar 2003 16:54:32 -0800
On Fri, Mar 14, 2003 at 4:03 PM, Adam J. Richter wrote:
> On Fri, 14 Mar 2003, Russell King wrote:
> >On Fri, Mar 14, 2003 at 12:28:47PM -0800, Adam J. Richter wrote:
> >> There was tangential mention in that thread
> >> of a "/proc/serialdev" interface, but nobody really identified any
> >> real benefit to it over the existing "uart: unknown" system.
> >There is one benefit, which would be to get rid of some of the yucky
> >mess we currently have surrounding the implementation of stuff which
> >changes the port base address/irq.
> >Currently, we have to check that we're the only user, shutdown, tweak
> >stuff, hope it all goes to plan, and start stuff back up again. If
> >something fails, we have to pray we can go back to the original setup
> >without stuff breaking. If that fails, we mark the port "unknown".
> >All of this would be a lot simpler if we didn't have the
> port actually
> >open at the time we change these parameters. We could just lock the
> >port against opens, check no one was using it, tweak the settings,
> >and release the port. If the changes fail, just report the failure.
> When I filter out prejudicial terminology like "yucky mess",
> "pray", "just", etc., I don't see a convincing explanation of how one
> approach is going to result in a lower line count, fewer branches,
> smaller kernel footprint, faster execution, new capabilities or any
> other relevant measure that I can think of in comparison to the
> existing approach.
> [ snip ]
Oh, but he _did_ give you information about such things. You filtered out
the real message. Allow me to expand the macros ...
yucky mess = referenced area has an unnecessarily complex control
structure. (more branches & code, slower ...)
just = fundamental simplification of the algorithm. (less code and
branching needed because less to do, smaller, faster ...)
hope, pray = referenced area can generate complex errors that cannot
be handled efficiently due to architectural limitations.
(more local error handling code and branching, bigger, slower ...)
expert opinion != prejudicial speech.
Read it again. You'll get the hang of it :-)
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