[lwip-users] [lwip] struct packing

[James Roth]

Hi,

    I'm porting lwIP to KROS rtos on Altera's Nios 32 processor using 
gcc.  Some issues I've run into:

    1.  struct packing

        Using #define PACK_STRUCT_FIELD(x) x __attribute__((packed)) 
does not seem to pack the structs.

        Doing this does work:

        struct foo
        {
            struct x bar __attribute__ ((packed));
            sturct x sss __attribute__((packed))
        } __attribute__ ((packed));

        It seems that it does not work without that last packed attribute.

    2. more packing:

        After I have added the extra attribute to the structs, the 
ethernet frame is recognized as an IP packet with correct version number 
etc.  I suspect that there are other structs to be packed.  lwIP sends 
continuous arp requests for the ip address on its own default interface.

    Should I try to repack the ethernet frame from within the 8900a 
driver?  Would I have to re-pack differently for each ip or arp packet 
type, or can it be generalized to 2 cases?

--
James


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