From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Yong Zhang <yong.zhang0@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Tony Luck <tony.luck@intel.com>,
Ralf Baechle <ralf@linux-mips.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mundt <lethal@linux-sh.org>,
Chris Metcalf <cmetcalf@tilera.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Mike Frysinger <vapier@gentoo.org>,
Hirokazu Takata <takata@linux-m32r.org>,
Richard Kuo <rkuo@codeaurora.org>,
David Howells <dhowells@redhat.com>, Bob Liu <lliubbo@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Richard Weinberger <richard@nod.at>,
Jesper Nilsson <jesper.nilsson@axis.com>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Matt Turner <mattst88@gmail.com>,
nikunj@linux.vnet.ibm.com
Subject: Re: [PATCH 01/27] smpboot: Provide a generic method to boot secondary processors
Date: Sun, 03 Jun 2012 17:35:54 +0530 [thread overview]
Message-ID: <4FCB5322.3050707@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120603113948.GC15354@n2100.arm.linux.org.uk>
On 06/03/2012 05:09 PM, Russell King - ARM Linux wrote:
> On Sun, Jun 03, 2012 at 05:03:50PM +0530, Srivatsa S. Bhat wrote:
>> That's a good point! But unfortunately we can't do that just yet.
>> Because, some architectures have explicit comments that say that
>> irqs must be enabled at a certain point in time, or have something
>> special than just a local_irq_enable(), and hence fall under the
>> __cpu_post_online() function when converted to this model.
>>
>> Examples: ARM (patch 26) and ia64 (patch 15)
>>
>> Unless the maintainers give a go-ahead to change them, I don't
>> think it would be safe.. (I have added the Notes section to each
>> patch to get the attention of the maintainers to such issues).
>
> I have no intention of touching ARMs SMP bringup any more than is
> absolutely necessary - this code is extremely fragile, and it's taken
> a long time to get it to where it presently is, where most people are
> happy with it.
>
> Especially problematical is stuff like where we enable interrupts in
> relation to other activities.
>
> It's probably best to describe the code not as "mostly bug free" but
> as "causes the least pain" because I don't think there is a solution
> which satisfies all the constraints placed upon this code path by
> the various parts of the kernel.
>
Thanks for your comments Russell. I understand your concerns. So, the
ARM patch does no functional change and retains how and where the
interrupts are enabled. And from looking at what you said above about
the bringup being fragile, I think even in future you wouldn't want any
functional changes to ARM just to make it fit into some generic model.
Thanks for the clarification.
However, what are your thoughts on the existing ARM patch (patch 26)
(which doesn't cause any functional changes)? That shouldn't pose any
problems right?
Regards,
Srivatsa S. Bhat
next prev parent reply other threads:[~2012-06-03 12:06 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-01 9:10 [PATCH 00/27] Generic framework for SMP booting/CPU hotplug related code Srivatsa S. Bhat
2012-06-01 9:10 ` [PATCH 01/27] smpboot: Provide a generic method to boot secondary processors Srivatsa S. Bhat
2012-06-01 12:09 ` Srivatsa S. Bhat
2012-06-03 8:51 ` Yong Zhang
2012-06-03 11:22 ` Srivatsa S. Bhat
2012-06-04 2:18 ` Yong Zhang
2012-06-03 8:53 ` Yong Zhang
2012-06-03 11:33 ` Srivatsa S. Bhat
2012-06-03 11:39 ` Russell King - ARM Linux
2012-06-03 12:05 ` Srivatsa S. Bhat [this message]
2012-06-01 16:51 ` Sam Ravnborg
2012-06-01 22:29 ` Srivatsa S. Bhat
2012-06-04 10:32 ` Thomas Gleixner
2012-06-04 13:07 ` Srivatsa S. Bhat
2012-06-04 13:18 ` Thomas Gleixner
2012-06-04 16:53 ` Srivatsa S. Bhat
2012-06-05 5:11 ` Yong Zhang
2012-06-05 6:07 ` Srivatsa S. Bhat
2012-06-01 16:53 ` Sam Ravnborg
2012-06-01 22:41 ` Srivatsa S. Bhat
2012-06-02 15:16 ` Sam Ravnborg
2012-06-02 15:34 ` Srivatsa S. Bhat
2012-06-01 9:10 ` [PATCH 02/27] smpboot: Add provisions for arch-specific locking around cpu_online_mask Srivatsa S. Bhat
2012-06-01 12:12 ` Srivatsa S. Bhat
2012-06-01 9:11 ` [PATCH 04/27] smpboot, x86, xen: Determine smp booting implementations at run-time Srivatsa S. Bhat
2012-06-01 9:11 ` [PATCH 05/27] xen, cpu hotplug: Don't call cpu_bringup() in xen_play_dead() Srivatsa S. Bhat
2012-06-01 12:59 ` [Xen-devel] " Jan Beulich
2012-06-01 15:13 ` Srivatsa S. Bhat
2012-06-01 15:36 ` Jan Beulich
2012-06-02 18:06 ` Srivatsa S. Bhat
2012-06-05 16:49 ` Konrad Rzeszutek Wilk
2012-06-05 17:36 ` Srivatsa S. Bhat
2012-06-05 17:40 ` Thomas Gleixner
2012-06-05 17:48 ` Srivatsa S. Bhat
2012-06-01 9:11 ` [PATCH 06/27] xen, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-01 9:11 ` [PATCH 07/27] x86, " Srivatsa S. Bhat
2012-06-04 14:29 ` Thomas Gleixner
2012-06-04 17:00 ` Srivatsa S. Bhat
2012-06-01 9:12 ` [PATCH 08/27] m32r: Fix horrible logic in smp_prepare_cpus() Srivatsa S. Bhat
2012-06-01 9:12 ` [PATCH 09/27] m32r, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-01 9:12 ` [PATCH 10/27] mips, " Srivatsa S. Bhat
2012-06-03 8:25 ` Yong Zhang
2012-06-03 11:48 ` Srivatsa S. Bhat
2012-06-04 2:17 ` Yong Zhang
2012-06-01 9:12 ` [PATCH 11/27] sh, " Srivatsa S. Bhat
2012-06-01 9:12 ` [PATCH 12/27] tile, " Srivatsa S. Bhat
2012-06-01 18:07 ` Chris Metcalf
2012-06-01 9:13 ` [PATCH 13/27] hexagon, " Srivatsa S. Bhat
2012-06-01 9:13 ` [PATCH 14/27] ia64: Move holding of vector_lock to __setup_vector_irq() Srivatsa S. Bhat
2012-06-01 9:13 ` [PATCH 15/27] ia64, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-01 9:13 ` [PATCH 16/27] mn10300: Fix horrible logic in smp_prepare_cpus() Srivatsa S. Bhat
2012-06-01 9:14 ` [PATCH 17/27] mn10300, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-03 8:33 ` Yong Zhang
2012-06-03 11:50 ` Srivatsa S. Bhat
2012-06-01 9:14 ` [PATCH 18/27] powerpc, " Srivatsa S. Bhat
2012-06-02 6:14 ` Paul Mackerras
2012-06-01 9:14 ` [PATCH 19/27] blackfin, " Srivatsa S. Bhat
2012-06-01 9:14 ` [PATCH 20/27] sparc64, " Srivatsa S. Bhat
2012-06-01 17:55 ` David Miller
2012-06-01 22:44 ` [UPDATED PATCH " Srivatsa S. Bhat
2012-06-01 22:52 ` David Miller
2012-06-01 9:15 ` [PATCH 21/27] sparc32, " Srivatsa S. Bhat
2012-06-01 17:56 ` David Miller
2012-06-01 18:54 ` Sam Ravnborg
2012-06-01 22:47 ` [UPDATED PATCH " Srivatsa S. Bhat
2012-06-01 22:53 ` David Miller
2012-06-01 23:17 ` Srivatsa S. Bhat
2012-06-02 6:52 ` Sam Ravnborg
2012-06-02 7:44 ` Sam Ravnborg
2012-06-02 8:01 ` Srivatsa S. Bhat
2012-06-02 8:14 ` Srivatsa S. Bhat
2012-06-02 15:13 ` Sam Ravnborg
2012-06-02 15:58 ` Srivatsa S. Bhat
2012-06-02 16:23 ` Sam Ravnborg
2012-06-02 16:34 ` Srivatsa S. Bhat
2012-06-03 21:17 ` [PATCH] sparc32: refactor smp boot Sam Ravnborg
2012-06-04 1:04 ` David Miller
2012-06-04 6:48 ` Srivatsa S. Bhat
2012-06-01 9:15 ` [PATCH 22/27] um, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-01 9:15 ` [PATCH 23/27] cris, " Srivatsa S. Bhat
2012-06-03 8:41 ` Yong Zhang
2012-06-03 11:52 ` Srivatsa S. Bhat
2012-06-01 9:15 ` [PATCH 24/27] parisc, " Srivatsa S. Bhat
2012-06-01 9:16 ` [PATCH 25/27] s390, " Srivatsa S. Bhat
2012-06-01 10:45 ` Heiko Carstens
2012-06-01 9:16 ` [PATCH 26/27] arm, " Srivatsa S. Bhat
2012-06-01 11:04 ` Russell King - ARM Linux
2012-06-01 9:16 ` [PATCH 27/27] alpha, " Srivatsa S. Bhat
[not found] ` <20120601091038.31979.67878.stgit@srivatsabhat.in.ibm.com>
2012-06-01 12:19 ` [PATCH 03/27] smpboot: Define and use cpu_state per-cpu variable in generic code Srivatsa S. Bhat
2012-06-01 12:25 ` Russell King - ARM Linux
2012-06-01 12:55 ` Srivatsa S. Bhat
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