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Message-ID: <20240409200314.GA2086199@bhelgaas>
Date: Tue, 9 Apr 2024 15:03:14 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: "Chen, Jiqian" <Jiqian.Chen@....com>,
"Rafael J . Wysocki" <rafael@...nel.org>
Cc: Roger Pau Monné <roger.pau@...rix.com>,
Len Brown <lenb@...nel.org>, Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
"xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
"Hildebrand, Stewart" <Stewart.Hildebrand@....com>,
"Huang, Ray" <Ray.Huang@....com>
Subject: Re: [RFC KERNEL PATCH v4 3/3] PCI/sysfs: Add gsi sysfs for pci_dev
[+to Rafael]
On Mon, Apr 08, 2024 at 06:42:31AM +0000, Chen, Jiqian wrote:
> Hi Bjorn,
> It has been almost two months since we received your reply last time.
> This series are blocking on this patch, since there are patches on Xen and Qemu side depending on it.
> Do you still have any confusion about this patch? Or do you have other suggestions?
> If no, may I get your Reviewed-by?
- This is ACPI-specific, but exposes /sys/.../gsi for all systems,
including non-ACPI systems. I don't think we want that.
- Do you care about similar Xen configurations on non-ACPI systems?
If so, maybe the commit log could mention how you learn about PCI
INTx routing on them in case there's some way to unify this in the
future.
- Missing an update to Documentation/ABI/.
- A nit: I asked about s/dumU/DomU/ in the commit log earlier,
haven't seen any response.
- Commit log mentions "and for other potential scenarios." It's
another nit, but unless you have another concrete use for this,
that phrase is meaningless hand waving and should be dropped.
- A _PRT entry may refer directly to a GSI or to an interrupt link
device (PNP0C0F) that can be routed to one of several GSIs:
ACPI: PCI Interrupt Link [LNKA] (IRQs 3 4 5 6 7 9 10 *11 12 14 15)
I don't think the kernel reconfigures interrupt links after
enumeration, but if they are reconfigured at run-time (via _SRS),
the cached GSI will be wrong. I think setpnp could do this, but
that tool is dead. So maybe this isn't a concern anymore, but I
*would* like to get Rafael's take on this. If we don't care
enough, I think we should mention it in the commit log just in
case.
Bjorn
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