Nicolai Hanssing wrote:
>
> Dear Listmembers
>
> First of a simple question most of you can propably answer:
>
> * Is operations on the fifos "atomic"?
> Both in userspace and in the rtkernel?
What do you mean by atomic?
Do you mean: Two threads writing to a fifo would mixup?
My understanding is when a system call is underway, it would
lock the inode it is operating on and do its action. But if
it finds that it can no longer write to pipe buffer, it could
as well put the writer process to sleep until a reader wakes up
makes space in the pipe buffer.
In that case, pipe operations wouldn't be atomic.
(PS: I am not very sure on the above. I am just making an avenue
for further discussion by *experts* :-)
>
> * Where can I find SSIZE_MAX [MAX bytesize for read()/write()]
> on an i3x86 2.2.18/19?
On a 2.2.14/12 it is in /usr/include/bits/posix1_lim.h
>
> * What is the max size of an fifo-queue?
> And unless it fails on initialisation there was enough
> kernelmemory - right?
>
> * Are there an "RTL_SSIZEMAX" for operations on the rtl_fifos?
>
> For some reason if havent been able to find any place in the manpages that
> states that the RTFIFOs are Atomic, though the fifos work as if they were
> ...
>
> --
>
> Next up is a problem with a simpel POSIX_thread:
>
> For some reason my thread keep chrashing the system [both in
> 2.2.18-rtlv3.0 and 2.2.19-rtlv3.1pre3]. I've been looking over the code
> throughly, and it seems allright. There's no dynamic memoryallocation, and
> only some simple IO to hardcoded adresses. I.e. it shouldnt chrash due to
> pointer-error or memory-leaks.
> However the thread uses some quite large variables, that according to my
> memmory are allocated on the stack (?).
>
> How can I tell if the stack runs out [has run out - overwrite kernelspace
> - whatever], and how can I increase the size
> dynammicly?
>
> --
>
> Hmm, maybe I should have spilt the mail i two - nahh I'll send you some
> other questions instead :-)
>
> Regards
> Nicolai Hanssing
>
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