[lwip-users] Interrupt-driven NIC driver with a Multi-threaded version of lwip

[Dan Lewis]

Hopefully someone can give me a bit of insight here. I've got lwip running 
(multithreaded with uC/OS-II), but it seems to occassionally hang if a packet 
arrives while another is being transmitted. My intuition tells me that the 
cause is an unprotected critical section, and I'm not certain that my software 
organization is compatible with the way lwip was intended to be used:

My Realtek RT8019AS Ethernet driver uses interrupts and uC/OS mailboxes for 
synchronization: The packet write routine (within lwip) pends waiting for an 
interrupt service routine to post to a mailbox when transmission of the 
previous packet is complete. Incoming packets are handled by a separate thread 
containing an infinite loop that pends waiting for the interrupt service 
routine to post to a mailbox when a new packet arrives. Note that the interrupt 
service routine only provides signaling; all transfer of data to/from the NIC 
is done in threads. To prevent interference between the packet read and packet 
write routines, each disables task switching (but not interrupts) while it is 
talking to the NIC.

Some details: 386EX cpu running in protected mode with a flat memory model. NIC 
is a RealTek RT8019AS. Using version 0.6 of lwip.

Basic question: Does lwip support this interrupt-driven approach in a 
multi-threaded context?

Thanks in advance!

Dan Lewis, Chair
Computer Engineering
Santa Clara University
Email: address@hidden