Ken,
It should be possible with this patch to fifos/rtl_fifo.c.
The handler installed via rtf_create_handler is now called
at the beginning of the Linux read call. I think this behaviour
makes more sense.
Michael.
--- rtl_fifo.c.ori Thu Jun 21 14:21:27 2001
+++ rtl_fifo.c Thu Jun 21 14:23:14 2001
@@ -509,6 +509,9 @@
minor = minor + RTF_BI(minor);
+ if ((result = (*RTF_HANDLER(minor)) (minor)) < 0) {
+ return result;
+ }
if (filp->f_flags & O_NONBLOCK) {
/* if (RTF_LOCK(minor))
return -EAGAIN;
@@ -542,15 +545,11 @@
rtl_spin_unlock_irqrestore(&RTF_SPIN(minor), interrupt_state);
buf += chars;
}
-/* RTF_LOCK(minor)--; */
if (read) {
inode->i_atime = CURRENT_TIME;
- if ((result = (*RTF_HANDLER(minor)) (minor)) < 0) {
- return result;
- }
- return read;
}
- return 0;
+/* RTF_LOCK(minor)--; */
+ return read;
}
> Reading the document more closely, however, reveals an explanation that says this
>facility is used in conjunction with rtf_get() to read data from the FIFO, after it
>is put there
> with a write(). My problem is the opposite. I want to put data into the FIFO,
>_from the rt side_ only when the Linux process is ready to read it. In other
>words... when it
> executes a read().
>
> It appears that what I am trying to do is not supported by RTLinux. If anyone can
>either confirm that or show me the error of my ways and explain how it _can_ be done,
>I'd
> appreciate it.
>
> Thanks.
>
> Ken
>
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