Upcall handler

Nicholas Clark nick at ccl4.org
Thu Dec 6 12:06:08 PST 2001

On Thu, Dec 06, 2001 at 07:39:15PM +0000, Peter Naulls wrote:
> Let's remove it.

Why do I remember the PRMs saying if you install any of Escape Handler/
Exit Handler/Upcall Handler you must install all 3?

> It was this handler that I finally removed that made all the difference
> to people suffering Lynx et. al.  occasionally locking up.  Probably the
> worst part is that having even an empty handler can cause a machine to
> lock up - usally provoked by our old friend, serial access.
> My conclusion when talking to John Tytgat recently was perhaps that
> perhaps it's some fault in the OS that makes this handler unsuitable to
> have in application space (obviously the SharedCLibrary uses it).
> Besides, the functionality it provides - handler removal, AFAICS, is
> called explictely anyway, by Unixlib's exec functionality.

What happens if user code does os_cli() on something that turns out to be
a new task?

[No, I'm not saying it's wrong to remove it. Just wondering what the PRMs
are on about]

Nicholas Clark

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