Re: [lwip-users] Data packets splitting on odd boundaries -> causes exception

[Michael Anburaj]

Hi Jani,

LwIP Source: Pulled from Savannah yesterday.

Application: Adam’s example code (18.1 Using the API
from lwip.pdf

Device platform: MIPS 4Kc processor running UCOS-II

Alignment requirement: 
byte access -1 byte boundary
halfword (16bit) access -2 byte boundary
word (32bit) access -4 byte boundary

Thanks,
-Mike.

--- Jani Monoses <address@hidden> wrote:
> It's not clear what the problem is
> Which version of lwIP are you using?
> What platform?Do data need specific alignment (2 or
> 4 byte)
> What application?The http example in the sources?
> 
> 
> > Hi,
> > 
> > I guess within the LwIP stack when large data
> packets
> > (HTTP packets) are sent in, they get split into
> tiny
> > packets & then get sent out. The console debug
> output
> > what I got indicates that the splitting could
> happen
> > on odd byte boundaries. Whereas the lwip_chksum()
> > routine in inet.c file assumes the pbuf payload
> > pointer address to be aligned on a half-word
> (16bit
> > address) boundary.
> > 
> > 
> > Console output clipping:
> > -----------------------
> > 
> > inet_chksum_pseudo(): checksumming pbuf 8014fa1c
> (has
> > next 0)
> > PBuf Flags: 0001
> > PBuf Ref Cnt: 0001
> > PBuf Payload ptr: 80118513
> > >[3e] <[3c] /[2f] B[42] O[4f] D[44] Y[59] >[3e]
> <[3c]
> > /[2f] h[68] t[74] m[6d] l[6c] >[3e] [00]
> > lwip_chksum(80118513, 16)
> > 
> > !!! Exception context !!!
> > BADVADDR: 0x80118513
> > CAUSE: 0x00808410
> > EPC: 0x8010ab5c
> > ERROREPC: 0x80102eec
> > DEL exception !!!
> > 
> > 
> > Please reply to me ASAP.
> > 
> > Thanks to Jani Monoses & Kieran Mansley for their
> > quick responses.
> > 
> > Thanks a lot,
> > -Mike.
> > 
> > 
> > __________________________________________________
> > Do you Yahoo!?
> > Yahoo! Shopping - Send Flowers for Valentine's Day
> > http://shopping.yahoo.com
> > 
> > 
> > _______________________________________________
> > lwip-users mailing list
> > address@hidden
> > http://mail.nongnu.org/mailman/listinfo/lwip-users
> 
> 
> _______________________________________________
> lwip-users mailing list
> address@hidden
> http://mail.nongnu.org/mailman/listinfo/lwip-users


__________________________________________________
Do you Yahoo!?
Yahoo! Shopping - Send Flowers for Valentine's Day
http://shopping.yahoo.com