[lkml]   [2018]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: linux-next: build failure after merge of the printk tree
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,

 \ /
  Last update: 2018-03-05 13:26    [W:0.114 / U:9.688 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site