[2024-feb-29] Sad news: Eric Layton aka Nocturnal Slacker aka vtel57 passed away on Feb 26th, shortly after hospitalization. He was one of our Wiki's most prominent admins. He will be missed.
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| — | es:howtos:software:rtai [2019/02/28 01:52 (UTC)] (actual) – creado slackwarespanol | ||
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| + | ====== RTAI ====== | ||
| + | <note important> | ||
| + | Under construction. | ||
| + | Please obtain example code from the [[https:// | ||
| + | </ | ||
| + | |||
| + | |||
| + | ===== Introduction ===== | ||
| + | |||
| + | RTAI is a system that allows your Linux operating system to run so-called ' | ||
| + | something regularly, to a schedule dictated by you, no matter how heavily loaded the system. | ||
| + | |||
| + | < | ||
| + | ===== Getting RTAI ===== | ||
| + | |||
| + | You can download the latest version of RTAI from the website: | ||
| + | |||
| + | < | ||
| + | # wget https:// | ||
| + | # tar xvf rtai-5.1.tar.bz2 | ||
| + | # cd rtai-5.1 | ||
| + | </ | ||
| + | |||
| + | ===== Identifying the HAL patch ===== | ||
| + | |||
| + | RTAI requires the application of kernel patches, but carries patches only for certain kernel versions. | ||
| + | |||
| + | < | ||
| + | # find ./ -name hal\*.patch | ||
| + | ./ | ||
| + | ./ | ||
| + | ./ | ||
| + | ./ | ||
| + | ./ | ||
| + | ./ | ||
| + | ./ | ||
| + | ./ | ||
| + | ./ | ||
| + | </ | ||
| + | |||
| + | Now check your own kernel version: | ||
| + | |||
| + | < | ||
| + | # uname -r | ||
| + | 4.4.14 | ||
| + | </ | ||
| + | |||
| + | We can see that the closest kernel with a HAL patch after this is 4.4.71, so that's the one to aim for. For now just copy the patch to the kernel source location: | ||
| + | |||
| + | < | ||
| + | # cp base/ | ||
| + | </ | ||
| + | |||
| + | ===== Switching Kernel Version ===== | ||
| + | |||
| + | We need to get ourselves on a kernel of the correct version (above) before we do anything else. Start by downloading and uncompressing the new version: | ||
| + | |||
| + | < | ||
| + | # cd /usr/src | ||
| + | # wget https:// | ||
| + | # tar xvf linux-4.4.71.tar.xz | ||
| + | # cd linux-4.4.71 | ||
| + | </ | ||
| + | |||
| + | Now use the existing configuration as a base and 'make oldconfig' | ||
| + | |||
| + | < | ||
| + | # zcat / | ||
| + | # make oldconfig | ||
| + | </ | ||
| + | |||
| + | If you have a more obscure filesystem for your root partition you may now want to 'make menuconfig' | ||
| + | |||
| + | < | ||
| + | # make | ||
| + | </ | ||
| + | |||
| + | And then copy the results to install: | ||
| + | |||
| + | < | ||
| + | # make modules_install | ||
| + | # cp arch/ | ||
| + | # cd /boot | ||
| + | </ | ||
| + | |||
| + | Edit the lilo config: | ||
| + | |||
| + | < | ||
| + | # vi / | ||
| + | </ | ||
| + | |||
| + | And ensure there' | ||
| + | |||
| + | < | ||
| + | image = / | ||
| + | root = /dev/sda1 | ||
| + | label = Linux-4.4.71 | ||
| + | read-only | ||
| + | </ | ||
| + | |||
| + | Leave the other kernel image section in there as a second option in case something goes wrong with the boot, but you want to make the new one the default (the first entry). | ||
| + | |||
| + | ===== Patching the Kernel ===== | ||
| + | |||
| + | When you're sure that new kernel works and your system boots and functions, now's the time to add the RTAI patches: | ||
| + | |||
| + | < | ||
| + | # cd / | ||
| + | # patch -p1 < / | ||
| + | </ | ||
| + | |||
| + | And now you can make the kernel again. | ||
| + | |||
| + | < | ||
| + | # make | ||
| + | </ | ||
| + | |||
| + | If there are any prompted questions about the RTAI it's safe to leave them as defaults. | ||
| + | Next install the new kernel. | ||
| + | |||
| + | < | ||
| + | # make modules_install | ||
| + | # cp arch/ | ||
| + | </ | ||
| + | |||
| + | You've already configured LILO, so just re-run it to reference the newly copied kernel: | ||
| + | |||
| + | < | ||
| + | # lilo | ||
| + | </ | ||
| + | |||
| + | Reboot the machine to ensure that the new kernel works. | ||
| + | |||
| + | ===== Compiling/ | ||
| + | |||
| + | Before compiling RTAI itself we must ensure / | ||
| + | |||
| + | < | ||
| + | # cd /usr/src | ||
| + | # rm linux | ||
| + | # ln -s linux-4.4.71 linux | ||
| + | </ | ||
| + | |||
| + | Next just compile in the normal way: | ||
| + | |||
| + | < | ||
| + | # cd rtai-5.1 | ||
| + | # ./configure | ||
| + | # make | ||
| + | # make install | ||
| + | </ | ||
| + | |||
| + | At this point, some kernel modules should have arrived in / | ||
| + | For now you can load them manually, however in the future you can add them to / | ||
| + | |||
| + | < | ||
| + | # / | ||
| + | # / | ||
| + | # / | ||
| + | </ | ||
| + | |||
| + | Check they are there: | ||
| + | |||
| + | < | ||
| + | # lsmod | grep rtai | ||
| + | rtai_fifos | ||
| + | rtai_sched | ||
| + | rtai_hal | ||
| + | </ | ||
| + | |||
| + | Now we need to ensure we can link to the libraries: | ||
| + | |||
| + | < | ||
| + | vim / | ||
| + | </ | ||
| + | |||
| + | Add the line: | ||
| + | |||
| + | < | ||
| + | / | ||
| + | </ | ||
| + | |||
| + | and then run (as root): | ||
| + | |||
| + | < | ||
| + | # ldconfig | ||
| + | </ | ||
| + | |||
| + | Finally, we are ready to write our first RTAI program. | ||
| + | |||
| + | ===== Example Program ===== | ||
| + | |||
| + | Here's an example Makefile to compile a really simple realtime program. | ||
| + | |||
| + | < | ||
| + | CC = $(shell / | ||
| + | LXRT_CFLAGS = $(shell / | ||
| + | LXRT_LDFLAGS = $(shell / | ||
| + | |||
| + | all:: rtai-example | ||
| + | |||
| + | rtai-example: | ||
| + | $(CC) $(LXRT_CFLAGS) -o $@ $< $(LXRT_LDFLAGS) -llxrt | ||
| + | | ||
| + | clean:: | ||
| + | $(RM) -f rtai-example *~ | ||
| + | | ||
| + | .PHONY: clean | ||
| + | </ | ||
| + | |||
| + | And here is the demo program, rtai-example.c: | ||
| + | |||
| + | < | ||
| + | TODO | ||
| + | </ | ||
| + | |||
| + | ===== Dedication ===== | ||
| + | |||
| + | This page is dedicated to the memory of captain@captain.at whos pages have been a great source of information | ||
| + | in kernel and realtime programming. | ||
| + | |||
| + | RIP Captain. | ||
| + | |||
| + | ====== Sources ====== | ||
| + | * Originally written by [[wiki: | ||
| + | |||
| + | {{tag> | ||
