720fc43a31
Ran these commands:
cvs -d:pserver:anonymous@cvs.gna.org:/cvs/rtai co vulcano
cd vulcano
git init
git add .
git commit
57 lines
2.2 KiB
Text
57 lines
2.2 KiB
Text
User space RTAI syscalls have 16 extensions slots. They allow any user to
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extend RTAI with her/his own user space callable APIs without touching
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RTAI itself. For the most efficient inline usage of any extension user slots
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must be assigned statically. RTAI itself uses a few extension slots for some
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of its native addons, as listed below.
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Those already used by modules found in this distributions are:
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0 - RTAI itself (hardwired),
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1 - tasklets (hardwired),
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2 - watchdog (hardwired),
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9 - comedi,
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10 - fifos,
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14 - serial,
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15 - rtdm.
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So you can reuse the above slots only if you are not using the related modules
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found in this distribution. In any case check the value returned by:
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set_rt_fun_ext_index.
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N.B. "(hardwired)" above means they are assumed as basic RTAI proper extensions.
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Nonetheless extension 1 and 2 do check if they can install into their hardwired
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slots, exiting their installation in error if they cannot.
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So you can make the related slot yours if neither tasklets nor watchdog are
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being used by your applications; __NEVER__ USE 0 though.
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In any case you'd better choose the other many free slots available to avoid
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any trouble.
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If in doubt about slots engaged already use something like the following piece
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of code in your extension module to discover them:
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#define MAX_LXRT_EXT 16
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do {
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int i;
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struct rt_fun_entry fun;
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for (i = 0; i < MAX_LXRT_EXT; i++) {
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if (set_rt_fun_ext_index(&fun, i) < 0) {
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rt_printk("< LXRT SLOT %d ENGAGED >\n", i);
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} else {
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reset_rt_fun_ext_index(&fun, i);
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}
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}
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} while (0);
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It has been already said above but, if you are still asking yourself why there
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is a forced staticalization of LXRT extension slots assignment, while it
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would be trivial to have functions to get/free slots dynamically, think about
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efficiency first, especially if direct (eager in the related RTAI config
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caption) inlining is used.
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WARNING
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If you intend to use Linux i386 with REGPARM configured notice that all your
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functions callable from user space must be prefixed with "RTAI_SYSCALL_MODE".
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In such a way they will be usable both with and without REGPARM. If you do
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not do so then avoid configuring REGPARM for Linux, which is not possible from
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2.6.20 onward, where REGPARM is the only way to operate and so it is an option
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no more.
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