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Date:   Wed, 30 May 2018 01:22:10 -0700
From:   okaya@codeaurora.org
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Christoph Hellwig <hch@infradead.org>, linux-pci@vger.kernel.org,
        timur@codeaurora.org, linux-arm-msm@vger.kernel.org,
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        Jonathan Corbet <corbet@lwn.net>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Christoffer Dall <cdall@linaro.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Marc Zyngier <marc.zyngier@arm.com>,
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        Thymo van Beers <thymovanbeers@gmail.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        David Rientjes <rientjes@google.com>,
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        Keith Busch <keith.busch@intel.com>,
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Subject: Re: [PATCH] PCI: Add pci=safemode option
In-Reply-To: <577f01ada5e7f08c79a28d41020fb019@codeaurora.org>
References: <1527650389-31575-1-git-send-email-okaya@codeaurora.org>
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On 2018-05-30 00:56, okaya@codeaurora.org wrote:
> On 2018-05-30 00:48, Greg Kroah-Hartman wrote:
>> On Wed, May 30, 2018 at 12:44:29AM -0700, okaya@codeaurora.org wrote:
>>> On 2018-05-30 00:37, Christoph Hellwig wrote:
>>> > On Tue, May 29, 2018 at 09:41:33PM -0700, Sinan Kaya wrote:
>>> > > Bjorn and I discussed the need for such a "safe" mode feature when you
>>> > > want to bring up PCI for a platform. You want to turn off everything
>>> > > as
>>> > > a starter and just stick to bare minimum.
>>> >
>>> > Can we please make it a config option the instead of adding code
>>> > to every kernel?  Also maybe the bringup should be in the name
>>> > to make this more clear?
>>> 
>>> One other requirement was to have a runtime option rather than 
>>> compile time
>>> option.
>>> 
>>> When someone reported a problem, we wanted to be able to say "use 
>>> this
>>> option and see if system boots" without doing any bisects or 
>>> recompilation.
>>> 
>>> This would be the first step in troubleshooting a system to see if
>>> fundamental features are working.
>> 
>> That makes sense, people can not rebuild their kernels for the most
>> part.  Putting it behind a config option would not make sense as it
>> would always have to be enabled.
>> 
> 
> Here is where the discussion took place. Last 5-10  messages should 
> help.
> 
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=196197
> 

Some more paper trail for general awareness.

https://lkml.org/lkml/2018/5/3/509

> 
>>> I don't mind changing the name Bjorn mentioned safe option. I made it
>>> safemode. I am looking at Bjorn for suggestions at this moment.
>> 
>> "minimal"?  "basic"?  "crippled"?
>> "my_hardware_is_so_borked_it_needs_this_option"?  :)
>> 
>> Naming is hard...
>> 
>> greg k-h