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From: Ingo Molnar <mingo@kernel.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	live-patching@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>, Jiri Slaby <jslaby@suse.cz>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC PATCH 00/10] x86: undwarf unwinder
Date: Thu, 1 Jun 2017 08:08:24 +0200	[thread overview]
Message-ID: <20170601060824.wv2go3adbvx5ptmt@gmail.com> (raw)
In-Reply-To: <cover.1496293620.git.jpoimboe@redhat.com>


* Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> Here's the contents of the undwarf.txt file which explains the 'why' in
> more detail:

Ok, so the code quality looks pretty convincing to me - the new core 'undwarf' 
unwinder code is a _lot_ more readable than any of the Dwarf based attempts 
before.

That we control the debug info generation at build time is icing on the cake to 
me.

One thing I'd like to see on the list of benefits side of the equation is a size 
comparison of kernel .text, with frame pointers vs. undwarf, on 64-bit kernels.

Being able to generate more optimal code in the hottest code paths of the kernel 
is the _real_, primary upstream kernel benefit of a different debuginfo method - 
which has to be weighed against the pain of introducing a new unwinder. But this 
submission does not talk about that aspect at all, which should be fixed I think.

Thanks,

	Ingo

  parent reply	other threads:[~2017-06-01  6:08 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-01  5:44 [RFC PATCH 00/10] x86: undwarf unwinder Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 01/10] objtool: move checking code to check.c Josh Poimboeuf
2017-06-14  7:22   ` Jiri Slaby
2017-06-01  5:44 ` [RFC PATCH 02/10] objtool, x86: add several functions and files to the objtool whitelist Josh Poimboeuf
2017-06-14  7:24   ` Jiri Slaby
2017-06-14 13:03     ` Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 03/10] objtool: stack validation 2.0 Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 04/10] objtool: add undwarf debuginfo generation Josh Poimboeuf
2017-06-14  8:42   ` Jiri Slaby
2017-06-14 13:27     ` Josh Poimboeuf
2017-06-22  7:47       ` Jiri Slaby
2017-06-22 12:49         ` Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 05/10] objtool, x86: add facility for asm code to provide CFI hints Josh Poimboeuf
2017-06-01 13:57   ` Andy Lutomirski
2017-06-01 14:16     ` Josh Poimboeuf
2017-06-01 14:40       ` Andy Lutomirski
2017-06-01 15:02         ` Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 06/10] x86/entry: add CFI hint undwarf annotations Josh Poimboeuf
2017-06-01 14:03   ` Andy Lutomirski
2017-06-01 14:23     ` Josh Poimboeuf
2017-06-01 14:28       ` Josh Poimboeuf
2017-06-01 14:39         ` Andy Lutomirski
2017-06-01 15:01           ` Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 07/10] x86/asm: add CFI hint annotations to sync_core() Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 08/10] extable: rename 'sortextable' script to 'sorttable' Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 09/10] extable: add undwarf table sorting ability to sorttable script Josh Poimboeuf
2017-06-01  5:44 ` [RFC PATCH 10/10] x86/unwind: add undwarf unwinder Josh Poimboeuf
2017-06-01 11:05   ` Peter Zijlstra
2017-06-01 12:26     ` Josh Poimboeuf
2017-06-01 12:47       ` Jiri Slaby
2017-06-01 13:02         ` Josh Poimboeuf
2017-06-01 13:42         ` Peter Zijlstra
2017-06-01 13:10       ` Peter Zijlstra
2017-06-01 12:13   ` Peter Zijlstra
2017-06-01 12:36     ` Josh Poimboeuf
2017-06-01 13:12       ` Peter Zijlstra
2017-06-01 15:03         ` Josh Poimboeuf
2017-06-14 11:45   ` Jiri Slaby
2017-06-14 13:44     ` Josh Poimboeuf
2017-06-01  6:08 ` Ingo Molnar [this message]
2017-06-01 11:58   ` [RFC PATCH 00/10] x86: " Josh Poimboeuf
2017-06-01 12:17     ` Peter Zijlstra
2017-06-01 12:33       ` Jiri Slaby
2017-06-01 12:52         ` Josh Poimboeuf
2017-06-01 12:57           ` Jiri Slaby
2017-06-01 12:47       ` Josh Poimboeuf
2017-06-01 13:25         ` Peter Zijlstra
2017-06-06 14:14           ` Sergey Senozhatsky
2017-06-01 13:50         ` Andy Lutomirski
2017-06-01 13:50     ` Ingo Molnar
2017-06-01 13:58       ` Jiri Slaby
2017-06-02  8:30         ` Jiri Slaby
2017-06-01 14:05       ` Josh Poimboeuf
2017-06-01 14:08       ` Jiri Slaby
2017-06-02 10:40         ` Mel Gorman

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