[Note]:  

Special options setting of lwIP in this project (for using it with uC/OS-II on TI C6000 DSP)

*******************************************************************************************
This port was for project ucos-lwip-c6x (http://gro.clinux.org/projects/ucos-lwip-c6x/). 

For the moment we were writing this note, lwIP v1.1.0 was used in this project. 

This note was written in Jan.22 2005 by zengming99@mails.tsinghua.edu.cn.
*******************************************************************************************

Usually, options of lwIP can be set in file "lwipopts.h". 

It was included by "opt.h", amd all options would be set as default value in "opt.h" 
if they were not defined in "lwipopts.h".

Each project should have its own "lwiports.h", and keep "opt.h" as it was.

In this project, for making lwIP work with uC/OS-II on a 32bits TI DSP, 
following options should be set:
------------------------------------------------------------------------------------

	1.  Define symbol "LWIP_PROVIDE_ERRNO" in compiler of CodeComposerStudio


	2.  #define MEM_ALIGNMENT 	4    (in "lwipopts.h" )
	    #define ETH_PAD_SIZE	2    (in "lwipopts.h" )
	
	    For the struct align problem on 32bits DSP.


	3.  #define ARP_QUEUEING	0 (in "lwipopts.h")
	
	    ARP_QUEUEING has a bug in lwIP v1.0.0 with TCP


	4.  #define LWIP_TASK_MAX	5 (in "sys_arch.h" )
	   #define LWIP_START_PRIO	5 (in "sys_arch.h" )

	   #define TCPIP_THREAD_PRIO	5 (in "lwipopts.h" )

	   That is, 5 lwIP threads were allowed, and default TCPIP_THREAD used priority 5.

	   So, user defined lwIP thread should have its priority between 6 ~ 9.


	5. #define  SYS_LIGHTWEIGHT_PROT	1		(in "lwipopts.h" )
	
	   #define SYS_ARCH_DECL_PROTECT(lev) 				(in "sys_arch.h" )
	   #define SYS_ARCH_PROTECT(lev) 	OS_ENTER_CRITICAL()	(in "sys_arch.h" )
	   #define SYS_ARCH_UNPROTECT(lev) 	OS_EXIT_CRITICAL()	(in "sys_arch.h" )

		These were very important when ethernet driver used intrrupt to check packet
	   and pBuf function was called in ISR.  Or else, uC/OS-II would run away.

		A much better and clean method is to set up a thread for the driver, in ISR 
	   just check packet and post MailBox to the thread.


Zeng, Ming

2005-01-18