From: Guenter Roeck <linux@roeck-us.net>
To: Qais Yousef <qsyousef@gmail.com>,
Paul Burton <paul.burton@imgtec.com>,
ralf@linux-mips.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
linux-mips@linux-mips.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] MIPS: Fix broken malta qemu
Date: Sat, 2 Apr 2016 07:05:05 -0700 [thread overview]
Message-ID: <56FFD191.70606@roeck-us.net> (raw)
In-Reply-To: <56FFB8B7.8050607@gmail.com>
On 04/02/2016 05:19 AM, Qais Yousef wrote:
> Hi Paul,
>
> On 01/04/2016 13:48, Paul Burton wrote:
>> On Thu, Mar 17, 2016 at 09:08:09PM +0000, Qais Yousef wrote:
>>> Malta defconfig compiles with GIC on. Hence when compiling for SMP it causes the
>>> new IPI code to be activated. But on qemu malta there's no GIC causing a
>>> BUG_ON(!ipidomain) to be hit in mips_smp_ipi_init().
>>>
>>> Since in that configuration one can only run a single core SMP (!), skip IPI
>>> initialisation if we detect that this is the case. It is a sensible behaviour
>>> to introduce and should keep such possible configuration to run rather than die
>>> hard unnecessarily.
>> Hi Qais/Ralf,
>>
>> This patch is insufficient I'm afraid. It's entirely possible to use SMP
>> with multiple VPEs in a single core on Malta boards that don't have a
>> GIC - we have code handling IPIs in that case guarded by #ifdef
>> CONFIG_MIPS_MT_SMP in arch/mips/mti-malta/malta-int.c. I think the
>> BUG_ON needs to be removed entirely, unless that single-core multi-VPE
>> IPI code is also converted to use an IPI irqdomain.
>>
>
> I was under the impression that SMP is only supported under GIC and older forms of SMP are deprecated.
>
> I think the problem you're describing is different to the one this is trying to fix. The right fix for your issue is to make CONFIG_GENERIC_IRQ_IPI selected when CONFIG_MIPS_GIC && !CONFIG_MIPS_MT_SMP.
>
Didn't Paul say that his system doesn't have a GIC ? Are you saying that he can not
(or no longer) run an image built for SMP on his system ?
Guenter
next prev parent reply other threads:[~2016-04-02 14:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-17 21:08 [PATCH] MIPS: Fix broken malta qemu Qais Yousef
2016-03-18 1:17 ` Guenter Roeck
2016-04-01 12:48 ` Paul Burton
2016-04-02 12:19 ` Qais Yousef
2016-04-02 14:05 ` Guenter Roeck [this message]
2016-04-04 6:41 ` Paul Burton
2016-04-04 7:59 ` [PATCH] MIPS: Don't BUG_ON when no IPI domain is found Paul Burton
2016-04-04 9:04 ` [PATCH v2] " Paul Burton
2016-04-04 8:02 ` [PATCH] MIPS: Fix broken malta qemu Ralf Baechle
2016-04-04 8:06 ` Paul Burton
2016-04-04 8:32 ` Ralf Baechle
[not found] ` <CA+mqd+7YA5JH=CfLBV9S-c+0aQw=NHihT+WyPvgUF6UkmK+tEQ@mail.gmail.com>
2016-04-04 8:40 ` Paul Burton
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