Dear all,
first of all thank you for this excellent work. Realtime Linux
is really an astonishing and remarkable piece of workmanship.
I am looking for a platform to drive a three axis stepper motor
milling machine, and neither DOS nor Linux would fit my needs
of generating parallel port signals at high rates. I'm currently
driving a small milling machine with a maximum step rate of about
1000/s; my intention is to drive another one which has a maximum
step rate of 11700/s. I hope RT-Linux will perform fast enough
for the latter, but I assume an ISA 486/DX-33 won't be sufficient?
Anyway, I have found three deficiencies I'd like to report, and added
one enhancement for my specific purposes as following:
1. The man page of rtf_put claims that -1 is returned in the
error case, and errno if set. Rather, rtf_put returns
the negated error code. The man page should reflect this.
2. A successful rtf_put doesn't return the number of bytes
written, as required, but rather 0. This should be changed
in the implementation by replacing "return count;" by
"return written;".
3. In 1.1 and before the rtf_select procedure returns "writable"
only when the fifo is RTF_EMPTY in the SEL_OUT case. Rather,
"writable" should be returned whenever the fifo is not
completely full (i.e, !RTF_FULL).
4. To fulfill my requirements I need the rt task to wait
for ever different periods. I do this by making it a
periodic task, and then calling rt_task_waitfor(RTIME).
This procedure is my replacement for rt_task_wait().
It waits for the given period, if not negative, for
the one specified during rt_task_make_periodic otherwise.
In rtl_sched.h I #define rt_task_wait() rt_task_waitfor(-1).
IMHO RT-Linux should immediately become an option in the 2.2 kernel
series. Besides making RT-Linux more publicly known this would also
ease the coordination of changes. Are there any plans to do so, or
alternatively to incorporate it into 2.3 in the future?
I recently tried to apply 2.0.D to the Linux 2.2.5 kernel. I made
some slight changes to the patches of Makefile and irq.c because two
hunks didn't succeed. However, the kernel doesn't boot anymore! Has
anybode else experienced this problem, or did I make something else
wrong?
Thanks for your patience with this rather long letter.
Regards,
Sebastian
--
Dipl.-Inform. Sebastian <dot> Wangnick <at eurocontrol in be>
Office: Eurocontrol Maastricht UAC, Horsterweg 11, NL-6191RX Beek,
Tel: +31-433661370, Fax: ~300
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For more information on Real-Time Linux see:
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