Re: [PATCH] POSIX timers for 2.3.25

Stephen C. Tweedie (sct@redhat.com)
Tue, 9 Nov 1999 13:42:26 +0000 (GMT)


Hi,

On Mon, 8 Nov 1999 21:46:05 +0100 (CET), Robert de Vries
<rhdv@rhdv.cistron.nl> said:

> On Mon, 8 Nov 1999, Matthew Wilcox wrote:
>> If this _really_ needs doing then we need a PER_NEWLINUX, change the
>> kernel internal structures to the way you want, then translate the
>> structures to the appropriate form for old Linux binaries whenever
>> delivering a signal. It'll be unpleasant.

> This _really_ needs doing, because not only RT signals issued by sigqueue
> and the timers need this sigev_value, but also signals sent by completion
> of asynchronous I/O and by the arrival of a message on an empty POSIX
> message queue.

Async IO completion signals use the same union as queued signals, so
si_sigval is still usable. If you want the same field for timer
signals, then change the _timer union in siginfo so that si_sigval is at
the right place. You can't just change the queued siginfo structure,
since that is already used by LinuxThreads.

> The asynchronous I/O at kernel level is curently under development at
> SGI (see http://oss.sgi.com/projects/kaio) and the POSIX mq_* family
> will need it next.

libaio-style async IO is defined in posix to use the normal queued
signals mechanism, so si_sigval doesn't need any change for that.

> I don't know if there are already loads of apps using RT signals out
> there. A simple recompilation would fix them anyway.

glibc uses them internally. No can change.

--Stephen

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