From: David Woodhouse <dwmw2@infradead.org>
To: Ard Biesheuvel <ardb@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linux-pci@vger.kernel.org, bhelgaas@google.com,
mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org,
Jeremy Linton <jeremy.linton@arm.com>,
Ali Saidi <alisaidi@amazon.com>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [EXTERNAL]arm64 PCI resource allocation issue
Date: Tue, 02 Aug 2022 10:18:38 +0100 [thread overview]
Message-ID: <d7328d63126096be3d631d013b02c30bbdd1524a.camel@infradead.org> (raw)
In-Reply-To: <CAMj1kXFWN80TENuP-0E09LEqrqqL2zoS3SDCeQE7aMZuBPA53Q@mail.gmail.com>
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On Tue, 2022-08-02 at 09:46 +0200, Ard Biesheuvel wrote:
> > If we want this, I would propose (happy to provide the implementation
> > but let's discuss the design first) something along the line of a
> > generic mechanism to "register" such a system device, which would add
> > it to a list. That list would be scanned on PCI device discovery for
> > BAR address matches, and the pci_dev/BAR# added to the entry (that or
> > put a pointer to the entry into pci_dev for speed/efficiency).
>
> This means that bus numbers cannot be reassigned, which I don't think
> we rely on today. To positively identify a PCI device, you'll need
> some kind of path notation to avoid relying on the bus numbers
> assigned by the firmware (this could happen for hot-pluggable root
> ports where no bus range has been reserved by the firmware)
That kind of path notation already exists for the Intel IOMMU, and
probably others. See dmar_match_pci_path(), dmar_pci_bus_add_dev() etc.
It would be good to lift that out and make it generic, rather than
reinventing another version.
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next prev parent reply other threads:[~2022-08-02 9:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-02 4:07 arm64 PCI resource allocation issue Benjamin Herrenschmidt
2022-08-02 7:46 ` Ard Biesheuvel
2022-08-02 9:18 ` David Woodhouse [this message]
2022-08-03 2:32 ` [EXTERNAL]arm64 " Benjamin Herrenschmidt
2022-08-03 2:31 ` arm64 " Benjamin Herrenschmidt
2022-08-04 10:36 ` Lorenzo Pieralisi
2022-08-04 23:51 ` Benjamin Herrenschmidt
2022-08-15 23:02 ` Benjamin Herrenschmidt
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