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Date: Sun, 16 Aug 2026 07:25:22 +0200
From: Lukas Wunner <lukas@wunner.de>
To: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Bjorn Helgaas <bhelgaas@google.com>, Thomas Gleixner <tglx@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
	"H. Peter Anvin" <hpa@zytor.com>, Jesse Barnes <jbarnes@hobbes.lan>,
	Ingo Molnar <mingo@elte.hu>, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/early-quirks: Scan all functions in
 early_pci_scan_bus()
Message-ID: <aoFJwldO-_qttr0P@wunner.de>
References: <20260807094601.263450-2-thorsten.blum@linux.dev>
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In-Reply-To: <20260807094601.263450-2-thorsten.blum@linux.dev>

On Fri, Aug 07, 2026 at 11:46:02AM +0200, Thorsten Blum wrote:
> early_pci_scan_bus() stops scanning a PCI slot when check_dev_quirk()
> returns nonzero, which avoids probing functions 1-7 on single-function
> devices, but also stops scanning when a function is absent on a
> multifunction device.
> 
> This can skip early quirks on multifunction devices with holes in their
> function numbering.
> 
> Check function 0 first, and if it indicates a multifunction device, scan
> functions 1-7 independently so that absent functions do not cause later
> ones to be skipped.

Which device do you need this for?  We should only scan additional
Functions if a quirk needs to applied to them because this extends
boot time.  It requires a justification and shouldn't be done "just
because".

Thanks,

Lukas