Learn RTOS

Like all in life: It depends.

Some commercial RTOS do some not. Some free RTOS use GPL and LGPL some other licenses.

Writing tests? Why would I do that? If there are bugs, my customers will report them.

I would expect that the more hard-realtime parts of your system may need to link to the kernel in ways that may cause the GPL to apply to those parts.

However, you may be able to do the realtime parts in kernel modules, but keep a lot of other parts of the system in proprietary userspace code.

The only major FOSS OS I know of that uses a pure GPL is Linux. So if your code really needs critical modifications to the kernel, you will have to publish those changes. However, Linux also has provisions for linking non-GPL'ed modules into the kernel (not everyone agrees that this is allowed under the GPL, but Linus says it's okay). Of course, Linux itself is not hard realtime in the first place - normally much of your code could go in user space (if it is *that* time-critical, you should be looking at a RTOS extension to Linux).

For FOSS OS's under modified GPLs (such as FreeRTOS), you can link your own non-GPL'ed files directly into the kernel. At most, you might add a few hooks to the original source code.

... snip ...

The original owner (who hasn't given up rights) has many options, even though he has released the software under the GPL (or equivalent). For example, I have released hashlib uner the GPL, but the documentation specifies that other licensing rights can be bought. So, for a fee, I can release the user from the obligation to release his source code. Hashlib adheres to the C standard, and so is fully portable. See:

This kind of "Linus says it's okay" claim seems to be the prevailing "wisdom", but no one ever seems to be able to cite any statement by Linus that is anywhere near that broad. See, for example:

Note that nowhere in that does Linus say outright that non-GPL'd modules are OK, but rather suggests that if you want to distribute a non-GPL'd module, you'd better be prepared to prove that it is not a derived work.

Linus is well-known for his pragmatism. He wants all kernel modules to be GPL'ed, but if a hardware supplier will only provide blob modules, he is not going to ban them. What he says in the article that you quoted is that his opinions on allowing non-GPL kernel modules does not count as a "get out of jail free" card. If you distribute a blob kernel module, and someone challenges your right to do so, it's up to *you* to defend it, not Linus.

The kernel has specific provisions for using non-GPL modules. These include a restricted interface for modules that don't state that they are GPL'ed, and "tainted" messages. Blob kernel modules do not have Linus' blessing, but they specifically and explicitly are not banned by him (though you will be cursed by RMS, of course).

Exactly my point. That's very far from saying that non-GPL kernel modules are "OK", yet many people seem to believe that Linus said that they are OK.

Though none of that actually provides any actual exception to the GPL license.

IMNSHO, any entity distributing a non-GPL kernel module is taking a lot of risk, because there are literally thousands of people that have standing to bring a copyright infringement suit against said entity.

Eric

I have downloaded silRTOS source with its MIPS32 port and pretty happy wit its small code size. It took just few hours to grasp entire silRTOS an infact within two day; i ran silRTOS with sample application on my custo MIPS32 board.

I got good impression and would encourage people to use silRTOS for:

1. Beginner of rtos who want to study RTOS & want to learn RTOS as sourc code available.

1. Low-Footprint, which can be used for low memory embedded product. (Lik what i was looking)

2. Optimized RTOS and low Task switch/ISR latency, which make no over-hea for embedded application.

1. Different processor architectures RTOS port available.

2. Free to use for commercial project and needn't to give a single penn or single line of code to silRTOS Author (Most important reason for me t use)

-Rob

po=

commercial

Thank you for your opinion. However, a couple of points about your article. Firstly, you should make some reference to the URL where you downloaded, without which no-one can follow you. Secondly, the act of top-posting has lost all the sequential information of the thread.

Please do not top-post. Your answer belongs after (or intermixed with) the quoted material to which you reply, after snipping all irrelevant material. See the following links:

(taming google)

The only way to get the source code is to send the author your email address , what is that all about !!

donald