From: Petr Mladek <pmladek@suse.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tejun Heo <tj@kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Linux-Next Mailing List <linux-next@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Dave Young <dyoung@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
akpm@linux-foundation.org, Andi Kleen <ak@linux.intel.com>
Subject: Re: linux-next: build failure after merge of the printk tree
Date: Mon, 5 Mar 2018 13:25:39 +0100 [thread overview]
Message-ID: <20180305122539.dakxwzxylyrv27od@pathway.suse.cz> (raw)
In-Reply-To: <20180303144739.GA516@tigerII.localdomain>
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
next prev parent reply other threads:[~2018-03-05 12:25 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-02 5:07 linux-next: build failure after merge of the printk tree Stephen Rothwell
2018-03-02 15:54 ` Petr Mladek
2018-03-03 2:43 ` Stephen Rothwell
2018-03-03 14:47 ` Sergey Senozhatsky
2018-03-05 3:20 ` Dave Young
2018-03-05 5:27 ` Greentime Hu
2018-03-05 5:41 ` Sergey Senozhatsky
2018-03-05 12:25 ` Petr Mladek [this message]
-- strict thread matches above, loose matches on Subject: below --
2023-01-15 23:23 Stephen Rothwell
2023-01-16 15:54 ` Petr Mladek
2022-11-21 0:00 Stephen Rothwell
2022-11-21 13:42 ` Petr Mladek
2021-07-20 7:43 Stephen Rothwell
2021-07-20 8:17 ` Naresh Kamboju
2021-07-20 12:28 ` Chris Down
2021-07-21 8:57 ` Petr Mladek
2021-07-21 11:22 ` Chris Down
2021-07-21 12:49 ` Petr Mladek
2021-07-22 23:01 ` Stephen Rothwell
2021-07-23 11:14 ` Petr Mladek
2021-07-23 12:14 ` Chris Down
2020-07-29 11:03 Stephen Rothwell
2020-07-29 11:47 ` Herbert Xu
2020-07-28 1:49 Stephen Rothwell
2020-07-28 1:51 ` Herbert Xu
2020-07-28 2:21 ` Stephen Rothwell
2020-07-28 1:54 ` Sergey Senozhatsky
2020-07-28 2:24 ` Stephen Rothwell
2020-06-21 3:15 Stephen Rothwell
2020-06-21 3:26 ` Herbert Xu
2020-06-23 0:26 ` Stephen Rothwell
2020-06-23 12:16 ` Petr Mladek
2020-06-23 12:19 ` Herbert Xu
2020-06-23 14:28 ` Petr Mladek
2020-06-23 15:17 ` Peter Zijlstra
2020-06-24 8:22 ` Petr Mladek
2020-06-24 0:20 ` Herbert Xu
2020-06-24 8:19 ` Petr Mladek
2020-06-24 8:21 ` Herbert Xu
2019-12-05 22:25 Stephen Rothwell
2019-12-06 10:03 ` Petr Mladek
2017-12-07 0:37 Stephen Rothwell
2017-12-07 1:26 ` Sergey Senozhatsky
2017-12-07 13:12 ` Petr Mladek
2017-12-06 3:23 Stephen Rothwell
2017-12-06 4:28 ` Sergey Senozhatsky
2017-12-06 10:17 ` Petr Mladek
2017-12-06 10:39 ` Sergey Senozhatsky
2017-12-07 1:24 ` Sergey Senozhatsky
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