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Date:   Wed, 9 Feb 2022 15:02:18 -0600
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Blazej Kucman <blazej.kucman@linux.intel.com>
Cc:     Nirmal Patel <nirmal.patel@linux.intel.com>,
        Kai-Heng Feng <kai.heng.feng@canonical.com>,
        Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>,
        linux-pci@vger.kernel.org, Blazej Kucman <blazej.kucman@intel.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Lukas Wunner <lukas@wunner.de>,
        Naveen Naidu <naveennaidu479@gmail.com>,
        Keith Busch <kbusch@kernel.org>,
        Jonathan Derrick <jonathan.derrick@linux.dev>
Subject: Re: [Bug 215525] New: HotPlug does not work on upstream kernel
 5.17.0-rc1
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On Wed, Feb 09, 2022 at 02:41:02PM +0100, Blazej Kucman wrote:
> On Thu, 3 Feb 2022 09:58:04 -0600
> Bjorn Helgaas <helgaas@kernel.org> wrote:

> > Why were you testing with "pci=nommconf"?  Do you think anybody uses
> > that with VMD and NVMe?
> 
> It was added long time ago when it was useful.

I'm curious about why it was useful.  It suggests a possible MMCONFIG
issue in firmware or in Linux.  If it was a Linux issue, ideally we
would fix that.  If it's a firmware issue, ideally we would work
around it or automatically turn on "pci=nommconf" so the user wouldn't
have to figure that out.

> Bugzilla report can be closed if you don't consider it as regression.

OK, I closed it with the details.  I'm not entirely convinced that
04b12ef163d1 ("PCI: vmd: Honor ACPI _OSC on PCIe features") was the
right thing, but I'll pursue that elsewhere.

Thanks for your patience in working through this, and sorry for the
hassle it caused you.

Bjorn