Re: [lwip-users] critical section protection + timer issues questions

[Peter Graf]

Scott Taggart wrote:

> [Snip]
>
> I do not want my threads to HAVE to call into the sys.c stuff JUST to 
> get the LWIP timer stuff to function.  As it is, I see no other 
> work-around – because the LWIP timer stuff DEMANDs that all threads 
> block in the previously mentioned 3 calls, I see no choice.

The lwIP timer implementation only requires a thread to use the lwIP 
specific sema/mailbox, where _this_ thread blocks on I/O through lwIP. 
You are free to block this thread using other methods at other times and 
places. You are also free to completely ignore the lwIP calls in threads 
that never use I/O through lwIP.

The only restriction is that you can not simply block for lwIP I/O and 
other I/O at the same time. If you have such a requirement, lwIP or the 
other I/O device needs to be polled. E.g. if you have a webbrowser which 
needs to block for keyboard input and for network packets. In such a 
case I block lwIP with a short timeout, poll the keyboard, then block 
lwIP again. Not elegant, but no noticable performance impact.

> I find this incredibly restrictive and arrogant – to presume that all
> threads on all o/ss must end up in some internal LWIP function call for
> the stack to work.

A more friendly tone might suit this friendly list better :-)

All the best
Peter