On Sat 2018-03-03 23:47:39, Sergey Senozhatsky wrote: > Cc-ing Tejun > > On (03/02/18 16:54), Petr Mladek wrote: > [..] > > > (Though it is not immediately obvious why.) > > > > It is a mistery to me. The error appears when I move any of > > dump_stack_print_info() or show_regs_print_info() function > > definitions from kernel/printk/printk.c to lib/dump_stack.c. > > All the other changes seems unrelated. > > > > The thing is that we basically do not touch dump_stack() definition > > by that patch. > > Apparently dump_stack_print_info() was in lib/dump_stack.c a long > time ago, but it was deliberately moved to printk.c, when kernel gained > a "generic" (dummy) dump_stack() fallback. Some archs, like blackfin, > define their own dump_stack() symbol and make it global via EXPORT_SYMBOL. > > In case of blackfin that arch-specific dump_stack() symbol invokes a > global dump_stack_print_info(). If we move dump_stack_print_info() back > to lib/dump_stack.c then we link both with arch/blackfin/dumpstack.o > and lib/dump_stack.o, which results in multiple definitions error. > If we move dump_stack_print_info() out on libdump_stack.o, then we > never link with lib/dump_stack.o Ah, I have finally understood the meaning of the libs-y kbuild variable. It is a nice source of these strange build failures. > ... so what are we going to do with that. > > a) we can drop the patch and cherry pick only the kexec part > > b) we can try to mark dummy lib/dump_stack() as __weak > EXPORT_SYMBOL and remove EXPORT_SYMBOL from arch-specific > definitions. Using the weak symbol makes perfect sense. I am going to look at the patch. Thanks a lot everybody for help. Best Regards, Petr -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
