Re: [lwip-devel] Understading LWIP_DEBUG()

[address@hidden]

Gisle Vanem wrote:
> What should I set $LWIP_DEBUG to to get some output? Tried
> '0x80', but nothing...
Looking at the definition of LWIP_DEBUGF, it depends on tree things: 
LWIP_DBG_ON, LWIP_DBG_TYPES_ON and LWIP_DBG_MIN_LEVEL. So every debug 
level 'debug' passed to LWIP_DEBUGF has to:
- have the flag 'LWIP_DBG_ON' set (0x80)
- have any of the flags in 'LWIP_DBG_TYPES_ON' set: LWIP_DBG_TRACE 
(0x40), LWIP_DBG_STATE (0x20), LWIP_DBG_FRESH (0x10) or LWIP_DBG_HALT 
(0x08) - depending on what LWIP_DBG_TYPES_ON is defined to
- have a level >= LWIP_DBG_MIN_LEVEL

So for a message for PING_DEBUG to be printed, this should be enough 
(LWIP_DBG_LEVEL_ALL defaults to 0 anyway):
#define PING_DEBUG    LWIP_DBG_ON
#define LWIP_DBG_TYPES_ON    
(LWIP_DBG_ON|LWIP_DBG_TRACE|LWIP_DBG_STATE|LWIP_DBG_FRESH|LWIP_DBG_HALT).

Now the LWIP_DBG_TYPES_ON is somewhat hard to understand, as most 
messages throughout the code don't use a type (i.e. only LWIP_DBG_ON). 
Therefore, to see these messages, you need the LWIP_DBG_ON bit in the 
definition of LWIP_DBG_TYPES_ON. However, you *can* define it to 
(LWIP_DBG_FRESH|LWIP_DBG_HALT) to only see messages from FRESH code or 
HALT conditions.

Hope that helps.

Simon