-1 from me as per this vote too sorry. I am sure there are other ways to accomplish that goal.
We do not want to communicate officially in any way that we are "NOT POSIX Compliant" on purpose when we clearly state in many places "strict POSIX and ANSI compliance" including the Inviolables. That will make us incoherent and self-contradictory. As in my previous response, trimming down the firmware in extreme cases can be achieved by removing unused functionalities, at the individual responsibility of the developer. I know there may be use cases for that, and people still want to use NuttX not the other RTOS, which is important. My proposition is to clearly mark all POSIX functionalities, that are enabled and available by default, and when any of them is removed then final solution is not POSIX compliant (may be not even used this is up to the firmware developer) but necessary to accomplish the task. This provides a choice for trimming down the firmware image but sticks to POSIX/ANSI by default. This way we stick to POSIX/ANSI compliance by default. We have clear identification of POSIX / PE51 parts. We allow trimming down the final firmware in known range of POSIX / PE51 or beyond. What do you think? :-) -- CeDeROM, SQ7MHZ, http://www.tomek.cedro.info On Thu, Nov 20, 2025 at 7:16 PM Gregory Nutt <[email protected]> wrote: > > -1 > > Bad idea. Destroys the core value proposition for the OS. > ________________________________ > From: Alan C. Assis <[email protected]> > Sent: Thursday, November 20, 2025 5:05 AM > To: [email protected] <[email protected]> > Subject: Re: [VOTE] Add support to NOT POSIX Compliant (or should be add > support ?) > > Hi Greg, > > Yes, I think the idea is to support POSIX subprofiles, this is the case for > pthread, posix timers, signals, etc. > > I think these extreme cases are low end MCUs where we can offer the option > to run a small version of NuttX, without jeopardizing the usage for people > who need a compliant POSIX OS. > > BR, > > Alan > > On Thu, Nov 20, 2025 at 9:50 AM Gregory Nutt <[email protected]> wrote: > > > There should only be extreme conditions where any POSIX API is > > non-compliant. POSIX complience is a core value of the OS and should not > > be violated. If we lose POSIX compliance then we have destroyed the > > meaning for the existence of the operating system. I hopr that no one will > > ever tolerate that to happen. > > > > The only legitimate cases I can think of are due to hardware limitations. > > For example, certain features of mmap() and fork() cannot be support if > > there is no MMU. uCLinux had the same limitations. > > ________________________________ > > From: Alan C. Assis <[email protected]> > > Sent: Thursday, November 20, 2025 4:39 AM > > To: dev <[email protected]> > > Subject: [VOTE] Add support to NOT POSIX Compliant (or should be add > > support ?) > > > > Hi Everyone, > > > > Some years ago NuttX was able to fit in really small MCUs (in fact I got it > > running on a chip using less than 2KB RAM). > > > > But a few years ago those options to disable SIGNALS, VFS, etc were > > disabled to create a system that was fully POSIX compliant. > > > > Unfortunately we missed the details: POSIX also aims at systems without > > resources, as is the case of POSIX PE51 (POSIX PSE51 is a specific, minimal > > profile or subset of the full POSIX - Portable Operating System Interface > > standard, formally defined in IEEE 1003.13-2003). > > > > Almost two years ago I opened an issue about it: > > https://github.com/apache/nuttx/issues/11390 > > > > Today Mr Chengdong opened a PR to bring back the possibility to disable > > signals: > > https://github.com/apache/nuttx/pull/17352 > > > > But as Mateusz (raiden00pl) pointed we need to be careful about it to avoid > > breaking the Inviolables: > > > > ## Strict POSIX compliance > > > > - Strict conformance to the portable standard OS interface as defined at > > OpenGroup.org. > > > > > > * - A deeply embedded system requires some special support. Special > > support must be minimized.* - The portable interface must never be > > compromised only for the sake of > > expediency. > > - Expediency or even improved performance are not justifications for > > violation of the strict POSIX interface. > > > > Fortunately Greg chose well his words: "Special support must be minimized". > > It doesn't mean it could exist, we just need to take care to not become > > normal or goal and jeopardize the system. > > > > So in this sense I propose to vote a suggestion: > > > > In the configuration where we already add an option to disable posix timer, > > pthreads, etc we add an option to "Enable POSIX PE51 subset". > > > > This way someone willing to disable signals will be aware he/she is > > creating a system that is not POSIX fully compliant or it is just a subset > > of a POSIX OS. > > > > BR, > > > > Alan > >
