Date:   Mon, 23 Jan 2023 14:33:01 -0600
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Mateusz =?utf-8?Q?Jo=C5=84czyk?= <mat.jonczyk@o2.pl>
Cc:     linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-acpi@vger.kernel.org, linux-i2c@vger.kernel.org,
        Bjorn Helgaas <bhelgaas@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>, Borislav Petkov <bp@suse.de>,
        Jean Delvare <jdelvare@suse.com>,
        Jean Delvare <jdelvare@suse.de>
Subject: Re: [PATCH v3 RESEND] acpi,pci: warn about duplicate IRQ routing
 entries returned from _PRT
Message-ID: <20230123203301.GA909338@bhelgaas>
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On Sat, Jan 21, 2023 at 04:33:14PM +0100, Mateusz Jończyk wrote:
> On some platforms, the ACPI _PRT function returns duplicate interrupt
> routing entries. Linux uses the first matching entry, but sometimes the
> second matching entry contains the correct interrupt vector.
>
> Print an error to dmesg if duplicate interrupt routing entries are
> present, so that we could check how many models are affected.

It shouldn't be too hard to use qemu to figure out whether Windows
uses the last matching entry, i.e., treating _PRT entries as
assignments.  If so, maybe Linux could just do the same.

Is anybody up for that?

Bjorn