Hi, On Tue Mar 13, 2018 at 11:58:57 +0800, Zihan Yang wrote: > I'm trying to debug L4Linux using jdb in Fiasco. I have added a > breakpoint in a function(e.g, syscall_exit), and it did hit into jdb > when I run. However, when I type 'bt' in jdb, it only prints the > values in the stack, or worse, it sometimes couldn't print the stack.
> I have tried enabling L4_DEBUG_REGISTER_NAMES and CONFIG_FRAME_POINTER > in L4Linux, and uncheck 'config without frame pointer' and 'generate > inline code' options in Fiasco, but still it doesn't work. > > QEMU could be an option, but qemu debugs the whole system while I just > want to focus on the L4Linux itself because I just want to figure out > the call path of ret_from_fork and how does L4Linux stop the user > dispatch loop, etc. > > Is there any way to show the the call path in jdb to assist the debugging > work? There's not really such a feature in jdb to assist with that. I think reading code is the better approach here. > By way, is there any doc describing the call path from fiasco to > L4Linux, I know it is implemented with sysretq or iretq, but where is > the entrypoint in L4Linux? For example, when I type 'ls /bin' in > shell, it would finally go into L4Linux's function 'syscall_exit()', > but how can I find the call path between them? If I can figure it out, > maybe I just don't need to debug anymore. All this entry to Linux and exit from it (to the user process) is happening in arch/l4/kernel/dispatch.c. There's the entry point (l4x_vcpu_entry) and that's the path to follow. In there it will branch to syscall handling, page fault handling, irq handling, or exception handling, depending on the type of entry. Adam _______________________________________________ l4-hackers mailing list l4-hackers@os.inf.tu-dresden.de http://os.inf.tu-dresden.de/mailman/listinfo/l4-hackers
