On 12 sep, 13:31, bapan wrote:
> Hi,
>
> I am planning to have patching functionalty for my router (processor
> MPC 604) running vxWorks 5.1.
> What I want is that suppose I modify a file a.c and load it using
> a.o(using ld command) I should be able to get the new functionality.
> For ex: Say my old function was
> void creatvlan() {
> ...
> ....
>
> }
>
> Now I modify this function to
> void creatvlan_new() {
> printf("Function name...\n");
>
> ...
> ..
>
> }
>
> Now any function which was calling creatVlan() should call/jump to
> creatvlan_new().
>
> I tried few things, but was not successful. So need help here:
> 1. I compiled the code with "mlongcall" option. So I could
> successfully load a.o using ld command.
> 2. But after using -mlongcall option, all "bl" instructions were
> modified to "blrl" instructions.
> 3. The strategy that I planned was, I would modify the first
> instruction of original function call with branch instruction to new
> function. So whenever someone calls the old function, it will actually
> jump to address of new function and therefore execute the new
> function.
> 4. But with "blrl" instruction, I couldn't do this as it probably uses
> LR register to jump.
>
> I couldn't figure out how/what to modify so that all calls to old
> function takes it to new function.
> Please help me on this.
>
> Thanks,
> Dutta

Hi,
You can easily search all symbol tables for specific symbols:
http://www-sgc.colorado.edu/~dixonc/...ef/symLib.html
Just look for creatvlan() symbol and wrap it with your
creatvlan_new(), it's a suggestion, I may be misunderstanding the.

--
Tarek