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Message-ID: <b5101b74da1c5b9feba5e95e8ed14ec8ed82bd24.camel@kernel.crashing.org>
Subject: Re: [PATCH 4/4] arm64: pci: acpi: Preserve PCI resources
 configuration when asked by ACPI
From:   Benjamin Herrenschmidt <benh@kernel.crashing.org>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc:     linux-pci@vger.kernel.org, Bjorn Helgaas <helgaas@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Sinan Kaya <okaya@kernel.org>, Ali Saidi <alisaidi@amazon.com>,
        Zeev Zilberman <zeev@amazon.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Date:   Sat, 22 Jun 2019 09:07:32 +1000
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On Fri, 2019-06-21 at 15:57 +0100, Lorenzo Pieralisi wrote:
> >        pci_assign_unassigned_root_bus_resources(bus);
> >   
> >        list_for_each_entry(child, &bus->children, node)
> 
> This is fine as far as we acknowledge that claiming resources
> on a bus is what should be done to make them immutable.

Well, as immuatable as it gets today. It's not perfect but it's a step
in the right direction. With the previous change in the series that
prevents auto-realloc when preserve_config is set, it will be
equivalent, in the current state of the code.

As part of my ongoing rework, I plan to look at making
IORESOURCE_PCI_FIXED more generally useful/robust, in which case we
could add that on top as well. That said, if we go down that path, I'm
keen on also adding a cmdline arg to ignore _DSM #5, if anything as a
test/diag tool when chasing problems caused by buggy BIOSes.

Cheers,
Ben.