POSIX 52 53? 54
Any one know any thing about a POSIX draft 52 or 53 or 54. I think they are suppose to have something to do with real time.
Where can they be found? What do they imply for the kernel?
George
POSIX 1003.13 defines profiles 51-4 where 51 is a single POSIX process with multiple threads (RTLinux) and 54 is a full POSIX OS with the RT extensions (Linux).
Quoted 11 lines · george anzinger
Any one know any thing about a POSIX draft 52 or 53 or 54. I think they are suppose to have something to do with real time.
Where can they be found? What do they imply for the kernel?
George
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--------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com
these are covered in IEEE P100.13, D9 September 1997 AD212. it is available from IEEE for a "nominal" fee.
they are 4 defined subsets of POSIX that are deemed appropriate for real-time systems.
unfortunately, the sub in subset is a small delta from the full set.
the subsets are:
PSE51: Minimal Realtime System Profile
PSE52: Realtime Controller System Profile
PSE53: Dedicated Realtime System Profile
PSE54: Multi-purpose Realtime System Profile.
now, PSE51 is already about 90% of POSIX, so I don't really see what is so minimal about it. the others require even more.
Quoted 28 lines · On Thu, 12 Apr 2001, [email protected] wrote:
POSIX 1003.13 defines profiles 51-4 where 51 is a single POSIX process with multiple threads (RTLinux) and 54 is a full POSIX OS with the RT extensions (Linux).
Quoted 11 lines · george anzinger
Any one know any thing about a POSIX draft 52 or 53 or 54. I think they are suppose to have something to do with real time.
Where can they be found? What do they imply for the kernel?
George
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Please read the FAQ at http://www.tux.org/lkml/Signature · 10 lines
--------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Signature · 11 lines
/*------------------------------------------------** ** Mark Salisbury | Mercury Computer Systems ** ** [email protected] | System OS - Kernel Team ** **------------------------------------------------** ** I will be riding in the Multiple Sclerosis ** ** Great Mass Getaway, a 150 mile bike ride from ** ** Boston to Provincetown. Last year I raised ** ** over $1200. This year I would like to beat ** ** that. If you would like to contribute, ** ** please contact me. ** **------------------------------------------------*/
Quoted 8 lines · Mark Salisbury
these are covered in IEEE P100.13, D9 September 1997 AD212. it is available from IEEE for a "nominal" fee.
they are 4 defined subsets of POSIX that are deemed appropriate for real-time systems.
unfortunately, the sub in subset is a small delta from the full set.
Quoted 8 lines
the subsets are:
PSE51: Minimal Realtime System Profile
PSE52: Realtime Controller System Profile
PSE53: Dedicated Realtime System Profile
PSE54: Multi-purpose Realtime System Profile.now, PSE51 is already about 90% of POSIX, so I don't really see what is so minimal about it. the others require even more.
Actually PSE51 seems to me to be pretty smart which is why, even though I swore we would never adopt the bloated, slow, POSIX standard for RTLinux, the discovery of 1003.13 changed my mind. PSE51 says a minimal RT system can look like a single process with "main" as the OS and with signal handlers and threads for applications. They note that POSIX does require "open/close/read/write", but in PSE51, we don't need to offer POSIX file
semantics: this is actually pretty nice for us. We install interrupt handlers with sigaction, use the thread/creation deletion and the standard synchronization API which I have grown to semi-like. 1003.13 gets around "fork" and such by simply adopting a "single process" semantics. According to the standard, we gotta have "fork", but it can fail due to too many processes (Linus hates this, but he thinks CC-NUMA scales, so ...) Basically, PSE51 allows for a real standard API without requiring the system to stop being hard realtime.
And then we have one thread as PS54 system so we can do
pthread_kill(linux_thread(), LINUX_IRQ +n)
to send interrupt "n" to Linux
And Alan Cox invented a brilliant method for fault tolerance where the PSE51 system runs a watchdog thread for the OS and has a recovery thread that does
vulture:
/* wait for death*/
pthread_join(linux_thread())
/* note that critical RT processing continues */
generate_blue_screen("NT EMULATION MODE ON: PLEASE BE PATIENT WHILE
WE RECOVER. .\n");
pthread_create(linux_thread(),&linux_attr,restart_linux,0);
goto vulture;This could be implemented quite easily.
Quoted 42 lines · On Thu, 12 Apr 2001, [email protected] wrote:
Quoted 28 lines
POSIX 1003.13 defines profiles 51-4 where 51 is a single POSIX process with multiple threads (RTLinux) and 54 is a full POSIX OS with the RT extensions (Linux).
Quoted 11 lines · george anzinger
Any one know any thing about a POSIX draft 52 or 53 or 54. I think they are suppose to have something to do with real time.
Where can they be found? What do they imply for the kernel?
George
-
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More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/Signature · 10 lines
--------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/Signature · 11 lines
/*------------------------------------------------** ** Mark Salisbury | Mercury Computer Systems ** ** [email protected] | System OS - Kernel Team ** **------------------------------------------------** ** I will be riding in the Multiple Sclerosis ** ** Great Mass Getaway, a 150 mile bike ride from ** ** Boston to Provincetown. Last year I raised ** ** over $1200. This year I would like to beat ** ** that. If you would like to contribute, ** ** please contact me. ** **------------------------------------------------*/
Signature · 4 lines
--------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com