From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v2 0/7] Allow disabling HW_BREAKPOINTS, PERF_EVENTS,
	INSTRUCTION_DECODER, IRQ_WORK, ANON_INODES
Date: Mon, 10 Mar 2014 08:43:54 +0100
Message-ID: <20140310074354.GA4890@gmail.com>
References: <cover.1394418994.git.josh@joshtriplett.org>
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Cc: kvm@vger.kernel.org, Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	David Herrmann <dh.herrmann@gmail.com>,
	Stephane Eranian <eranian@google.com>, linux-kernel@vger.kernel.org,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Paul Mackerras <paulus@samba.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andi Kleen <ak@linux.intel.com>, x86@kernel.org,
	Ingo Molnar <mingo@redhat.com>, oprofile-list@lists.sf.net,
	Mel Gorman <mgorman@suse.de>,
	Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
	Borislav Petkov <bp@suse.de>, Dave Young <dyoung@redhat.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>, Gleb Natapov <gleb@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>, Bin Gao <bin.gao@intel.com>,
	Matt Fleming <matt.fleming@intel.com>,
	Jacob Shin <jacob.shin@amd.com>, Oleg Nesterov <oleg@redhat.com>,
	T
To: Josh Triplett <josh@joshtriplett.org>
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* Josh Triplett <josh@joshtriplett.org> wrote:

> This patch series makes it possible to disable HW_BREAKPOINTS, 
> PERF_EVENTS, INSTRUCTION_DECODER, IRQ_WORK, and ANON_INODES.  
> Without this patch series, all of these config options get 
> automatically selected on x86, making them impossible to disable.
>
> This is a revival of a previous patch series from Andi Kleen sent in 
> October 2013. [...]

So my main problem with those patches was that if HW_BREAKPOINTS is 
disabled then GDB 'hbreak' isn't simply disabled but fails in various 
non-obvious ways, taking down the rest of GDB with it, so it's in 
essence an ABI and tool breaker which is not very useful.

If all of ptrace is disabled then it perhaps behaves more cleanly, but 
we didn't allow the disabling of ptrace in the past, and I'm not sure 
we should start with it today.

So it's still a NAK for the time being.

Thanks,

	Ingo

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