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From:   "Derrick, Jonathan" <jonathan.derrick@intel.com>
To:     "Busch, Keith" <keith.busch@intel.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "okaya@kernel.org" <okaya@kernel.org>,
        "willy@infradead.org" <willy@infradead.org>,
        "liudongdong3@huawei.com" <liudongdong3@huawei.com>,
        "helgaas@kernel.org" <helgaas@kernel.org>,
        "poza@codeaurora.org" <poza@codeaurora.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>
Subject: Re: [PATCH 1/2] PCI/DPC: Add 'nodpc' parameter
Thread-Topic: [PATCH 1/2] PCI/DPC: Add 'nodpc' parameter
Thread-Index: AQHUNN8oPZdeP/Rn10aUfkbk3uP46aTC/RYAgAAASYCAAE5egIAABWyAgAAIIACAAAKJAA==
Date:   Thu, 16 Aug 2018 21:28:45 +0000
Message-ID: <1534454924.13356.1.camel@intel.com>
References: <1534368400-2807-1-git-send-email-jonathan.derrick@intel.com>
         <20180816154940.GD5762@bombadil.infradead.org>
         <1534434641.17819.27.camel@intel.com>
         <20180816203111.GB10316@bhelgaas-glaptop.roam.corp.google.com>
         <1534452635.17819.53.camel@intel.com>
         <20180816211940.GB7400@localhost.localdomain>
In-Reply-To: <20180816211940.GB7400@localhost.localdomain>
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On Thu, 2018-08-16 at 15:19 -0600, Keith Busch wrote:
> On Thu, Aug 16, 2018 at 01:50:42PM -0700, Derrick, Jonathan wrote:
> > It can also be disabled with setpci, but is that any less of a
> > hassle?
> > Genuine question to understand your point of view.
>=20
> That is not a real solution, IMO. 'setpci' is good to inject things
> for testing, but it changes config space without the kernel aware
> that
> you've done that, so it is inherently racey with other kernel threads
> touching pci config space. And the kernel or platform may end up
> undoing
> what you had 'setpci' do anyway with no immediate way to be notified
> it
> was changed.

It sounds like a sysfs toggle could be useful regardless of the boot
parameter.
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