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From: Torsten Duwe <duwe@lst.de>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Anton Blanchard <anton@samba.org>,
	amodra@gmail.com, Jiri Kosina <jkosina@suse.cz>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	live-patching@vger.kernel.org
Subject: Re: [PATCH v6 1/9] ppc64 (le): prepare for -mprofile-kernel
Date: Thu, 28 Jan 2016 12:50:49 +0100	[thread overview]
Message-ID: <20160128115049.GE32095@lst.de> (raw)
In-Reply-To: <1453955219.4108.6.camel@ellerman.id.au>

On Thu, Jan 28, 2016 at 03:26:59PM +1100, Michael Ellerman wrote:
> 
> That raises an interesting question, how does it work *without* DYNAMIC_FTRACE?
> 
> It looks like you haven't updated that version of _mcount at all? Or maybe I'm
> missing an #ifdef somewhere?

You didn't, I did. I haven't considered that combination.

> It doesn't look like that will work right with the -mprofile-kernel ABI. And
> indeed it doesn't boot.

The lean _mcount should handle it and boot, had I not misplaced it in
the #ifdefs, but then of course profiling wouldn't work.

> So we'll need to work that out. I guess the minimum would be to disable
> -mprofile-kernel if DYNAMIC_FTRACE is disabled.

I feel that supporting all combinations of ABIv1/ABIv2, FTRACE/DYNAMIC_FTRACE,
-p/-mprofile-kernel will get us into #ifdef hell, and at least one kernel
developer will go insane. That will probably be the one porting this
to ppc64be (ABIv1).

> Frankly I think we'd be happy to *only* support DYNAMIC_FTRACE, but the generic
> code doesn't let us do that at the moment.

Seconded.
I'll have a look at the Kconfigs.

> But it's better than the previous version which didn't boot :)

That's your fault, you picked the wrong compiler ;-)

> Also ftracetest fails at step 8:
>   ...
>   [8] ftrace - function graph filters with stack tracer
>   Unable to handle kernel paging request for data at address 0xd0000000033d7f70
[...]
> That doesn't happen without your series applied, though that doesn't 100% mean
> it's your bug. I haven't had time to dig any deeper.

Will check as well...

	Torsten

  reply	other threads:[~2016-01-28 11:50 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-25 15:38 [PATCH v6 0/9] ftrace with regs + live patching for ppc64 LE (ABI v2) Torsten Duwe
2016-01-25 15:26 ` [PATCH v6 1/9] ppc64 (le): prepare for -mprofile-kernel Torsten Duwe
2016-01-27 10:19   ` Michael Ellerman
2016-01-27 10:44     ` Torsten Duwe
2016-01-28  4:26       ` Michael Ellerman
2016-01-28  4:26         ` Michael Ellerman
2016-01-28 11:50         ` Torsten Duwe [this message]
2016-01-27 12:58     ` Alan Modra
2016-01-27 13:45       ` Torsten Duwe
2016-01-28  3:39       ` Michael Ellerman
2016-01-28  3:39         ` Michael Ellerman
2016-02-03  7:23   ` AKASHI Takahiro
2016-02-03  8:55     ` Jiri Kosina
2016-02-03 11:24       ` Torsten Duwe
2016-02-04  9:31         ` AKASHI Takahiro
2016-02-04 11:02           ` Petr Mladek
2016-02-05  4:40             ` Balbir Singh
2016-02-05 10:22               ` Petr Mladek
2016-02-04 21:47           ` Jiri Kosina
2016-01-25 15:27 ` [PATCH v6 2/9] ppc64le FTRACE_WITH_REGS implementation Torsten Duwe
2016-01-25 15:29 ` [PATCH v6 3/9] ppc use ftrace_modify_all_code default Torsten Duwe
2016-01-25 15:29 ` [PATCH v6 4/9] ppc64 ftrace_with_regs configuration variables Torsten Duwe
2016-01-25 15:30 ` [PATCH v6 5/9] ppc64 ftrace_with_regs: spare early boot and low level Torsten Duwe
2016-01-25 15:31 ` [PATCH v6 6/9] ppc64 ftrace: disable profiling for some functions Torsten Duwe
2016-01-25 15:31 ` [PATCH v6 7/9] ppc64 ftrace: disable profiling for some files Torsten Duwe
2016-01-25 15:33 ` [PATCH v6 8/9] Implement kernel live patching for ppc64le (ABIv2) Torsten Duwe
2016-01-26 10:50   ` Miroslav Benes
2016-01-26 12:48     ` Petr Mladek
2016-01-26 13:56       ` Torsten Duwe
2016-02-02 12:12       ` Petr Mladek
2016-02-02 15:45         ` Torsten Duwe
2016-02-02 16:47           ` Petr Mladek
2016-02-02 20:39             ` Jiri Kosina
2016-01-26 14:00     ` Torsten Duwe
2016-01-26 14:14       ` Miroslav Benes
2016-01-27  1:53         ` Jessica Yu
2016-02-02 13:46   ` [PATCH v6 8/9] " Denis Kirjanov
2016-02-10 18:03     ` Torsten Duwe
2016-01-25 15:33 ` [PATCH v6 9/9] Enable LIVEPATCH to be configured on ppc64le and add livepatch.o if it is selected Torsten Duwe
2016-01-27 10:51 ` [PATCH v6 0/9] ftrace with regs + live patching for ppc64 LE (ABI v2) Balbir Singh
2016-01-27 12:19   ` Torsten Duwe
2016-01-28  2:41     ` Balbir Singh
2016-01-28  3:31       ` Michael Ellerman
2016-01-28 11:19         ` Torsten Duwe

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