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Subject: Re: [PATCH 2/2] PCI: Skip resource distribution when no hotplug
 bridges
From:   Benjamin Herrenschmidt <benh@kernel.crashing.org>
To:     Mika Westerberg <mika.westerberg@linux.intel.com>
Cc:     Bjorn Helgaas <helgaas@kernel.org>,
        Nicholas Johnson <nicholas.johnson-opensource@outlook.com.au>,
        Logan Gunthorpe <logang@deltatee.com>,
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Date:   Tue, 25 Jun 2019 22:23:33 +1000
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On Tue, 2019-06-25 at 15:04 +0300, Mika Westerberg wrote:
> > What's your experience in that area ? How (well) do they handle it in
> > the boot firmware ? at least on arm64, boot firmwares are rather
> > catastrophic when it comes to PCI, and on other embedded devices they
> > are basically non-existent.
> 
> Well my experience is quite limited to recent Macs and PCs which usually
> handle the initial resource allocation just fine. In case of Thunderbolt
> some "older" PCs handle everything in firmware, even the runtime
> resource allocation via SMI handler accompanied with ACPI hotplug.

Ah so this is what Lenovo calls "Thunderbolt firmware assist" in the
BIOS ? I turned that on, it did help with Linux :)

Cheers,
Ben.