Hi Leon, On Monday 20 June 2005 15:26, Leon Brits wrote: > I've "extracted" the E1000 driver code from the TFTP server to get some > packet data directly into L4. I've noticed that if I load this task with > the loader then the TX part sends garbage. I then added (for fun) the > attribute (section "STACK") to the buffer from which the packet is send > and now it works. > > Can anybody explain this to me! Send a link to some use full doc?
TFTP is more or less a hack. Most drivers were derived from GRUB and still GRUB is a hack. GRUB code "knows" that it runs one-by-one mapped, that is physical and virtual addresses are equal. Therefore in GRUB a network buffer can simply be allocated at the stack. In L4env, the stack isn't necessary 1-by-1 mapped (especially, if the task was started via the loader). Therefore, tftp starts a new thread using a _known_ stack (see main.c, function real_main()). I assume that specifiying the STACK attribute does the same in your application. 1-by-1 mapped memory is needed since the network card does not know of any virtual memory layout. Frank -- ## Dept. of Computer Science, Dresden University of Technology, Germany ## ## http://os.inf.tu-dresden.de/~fm3 ##
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