El 07/04/2012 16:02, Jim Lux escribió:
On 4/7/12 4:47 AM, Javier Herrero wrote:
I'm very familiar with the LEON and RTEMS, having managed a software
development project with it for the last 3 or 4 years at work.
http://www.gaisler.com/ for LEON
http://www.rtems.org/ for RTEMS
I will have a look to RTEMS
And yes, there is a port (maybe two) of Linux for the LEON as well (A
few years ago, we loaded up the Snapgear port, but since we went
RTEMS, I haven't fooled with it). You'd have to check the Gaisler.com
website.
I've done. The Snapgear port is quite old now, but the other port is
actively maintained and updated with current kernel.
You can drop a LEON core into a Virtex II in about a day, and judging
from the traffic on the LEON yahoo list (where the Gaisler folks hang
out), lots of people are doing things like multiple cores and things
on all manner of Xilinx eval boards.
And also for Altera (for example, the Terasic DE2-115 with a Cyclone IV)
and others. I've seen you int that list :) An I've seen implementations
for smaller FPGAs like the Spatarn 6LX25
RTEMS wise... It's pretty well supported by the community, it's open
source, it does all the stuff you want a RTOS to do. it's NOT a
multitasking, dynamic loading OS like Linux. That is it doesn't
support an MMU and process space isolation (although that might be
possible in newer versions.. there's a lot of configurability). It's
basically a statically linked single task with threads. They've got
RAM (and disk) file systems, IP stacks, a shell, YAFFS, etc.
Like all open source, there's quite a lot of interesting stuff
available (not from rtems.org, but others) that is 90% complete.
Somebody at Google Summer of Code or for their Masters decides to
implement something cool, and gets most of the way done, then wanders
away (the summer ended, they got their degree, the usual story).
But there's also a core of users who are serious and rigorous and
contribute back, so the main stuff in the distribution from Joel
Sherrill at OAR (who make RTEMS) is pretty rock solid.
I will learn more about RTEMS. For the application I've (and this links
directly to the message from Javier Serrano), the hardware platform is
one of the CERN Open Hardware ones, the SPEC. For the purpose and
interface needs, really an operating system is not required (no
filesystem, no TCP/IP needed, no multitasking, no framebuffer...), and
certainly a Linux would have a very large footprint without providing
any real help. And about the processor selection, the trade-off that
Javier exposes are the same I'm confronting. Both are open-sourced and
well supported, and in one side the LM32 is smaller, in the other the
LEON3 has more capabilities that can be implemented or not (like MMU or
FPU, and better multi-core support, although not currently needed in my
project). I probably will take the LEON3 road, but also because it is
more popular in my current field, but for now I usually do not need the
FT version since I'm more related with GSEs.
ESA has several rigorously verified flight qualified versions of RTEMS
(in Portugal and Austria, as I recall)
Yes, this is one of the reasons to gain experience in that road :) I
have some tendency to stay in Linux because I'm very familiarized with
it in the non-MMU implementations (for Blackfin) and also with MMU - and
I've found that for a small embedded system, to have the MMU is not so
important, even sometimes it is a drawback.
In any case we are running a bit OT (except considering that this
general discussion has timing applications, of course ;) ). Also I'm
happy to have found a time-nut colleage in other list, and probably I
will ask you some things about off-list in order to not increase noise,
if possible.
Best regards,
Javier
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