[lwip-users] Re: [lwip] sys_timeout()

[Peter Graf]

Hi Adam,

>The timer functionality is completely separate from the semaphores, message 
>queues, and threads of the underlying OS. The timers are completely
contained 
>within each thread and the OS will never even know that they exist. The 
>timers are *not* handled by the OS, but by the wrapper code in the sys_arch.c

As you said earlier, a timeout handler is never called, as long as the thread
asking for the timeout has not blocked. So somehow the timeout management must
know if the *right* thread is blocking for a sema/message. I do not (yet)
understand how timeout management can know that without

knowing sema/message status

or

knowing thread status information.

>Another problem with running lwIP in an environment such as the one you 
>describe might be that shared memory is used throughout the lwIP code. The 
>application programs and the TCP/IP stack uses shared memory to communicate. 
>The memory areas that are shared are the ram[] and memp_memory[] arrays in 
>the mem.c and memp.c files.

Yes, but that is a minor problem. Actually I think I have proper
implementations
for everything but the timer handling. Looks like I must cut my teeth into the
details of the Unix implementation in order to understand exactly how timeout
management aquires the necessary info.

All the best

Peter

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