From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8C97F2561AC; Tue, 22 Apr 2025 21:07:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745356027; cv=none; b=gB2ra4qi179iowzYfqvIHWZc0Y9ZIK4cf4zpRVIQASqEzl6iFIjrODJF/7BaiBPEYpI9qaM0CUqIWVsLjT+P1vC4ZaSW1GDqbHYsDJq6tOXbOwndVDO4vuFMK/tWCb7owMbWwCSDF9PRtu8T0Zo5oEjrl4suwIhQj/DjiuOuMJc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745356027; c=relaxed/simple; bh=uqukdnY8PqmQkUxEKFuIv/luw1k925DyIN7ppE2OqgE=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=oNwGNw2Rj9WRpuqG0dXmIoz5oGeoiw0Xbc5Oxo9wieXmVVOpYmuFcGipmv0wXufV+phtBPO4vV8x2g73Bdqs7JRWca7JjifvZkigMBdYDEMbDSMf/upOHuM602ZRZE7o8r4lCJw5L1Y8kLkiBuMcZyI7URE/L2+GIGO91+tnWLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AcMbH3tm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="AcMbH3tm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4A2AC4CEE9; Tue, 22 Apr 2025 21:07:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745356027; bh=uqukdnY8PqmQkUxEKFuIv/luw1k925DyIN7ppE2OqgE=; h=Date:From:To:Cc:Subject:From; b=AcMbH3tm3L4XU3n7hfmwHlCdPBVgbUuKIvM/MWa2wtQK/YnbyTP4o2zttihlhu959 5yqBEAK3rOsAaG124RDJmZ42GNoXomL3tO27dio6pikcYmId1lsNy3jkBuUMnM4hgy ZrB8qrAHgEbYhH1w2oUsJU7dPeXChvPAUoOze8A3v/fsTcvBxRNgCK8Aov7Lkj2TMd 5sa0Z8pMv9mHx0UOK9rwn3VDcCDY7I665DSmxbdyeH9SEQ/r5vWFIXOAK3nUVA3Q8j LIayJV2F2C5kzxN+FrhFhrInDpPBT/pyXjldiWBWCbtl4Tpontkvc/2v7/Alc71ZuY rQqGJoXYGKaJg== Date: Tue, 22 Apr 2025 16:07:05 -0500 From: Bjorn Helgaas To: Thomas Gleixner Cc: Jiri Slaby , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: IRQ domain logging? Message-ID: <20250422210705.GA382841@bhelgaas> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi Thomas, IRQ domains and IRQs are critical infrastructure, but we don't really log anything when we discover controllers or set them up. Do you think there would be any value in exposing some of this structure in dmesg to help people (like me!) understand how these are connected to devices and drivers? For example, in a simple qemu system: IOAPIC[0]: apic_id 0, version 32, address 0xfec00000, GSI 0-23 ACPI: Using IOAPIC for interrupt routing ACPI: PCI: Interrupt link LNKA configured for IRQ 10 ACPI: PCI: Interrupt link GSIA configured for IRQ 16 hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0 ACPI: \_SB_.GSIA: Enabled at IRQ 16 pcieport 0000:00:1c.0: PME: Signaling with IRQ 24 00:03: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A ata1: SATA max UDMA/133 abar m4096@0xfeadb000 port 0xfeadb100 irq 28 lpm-pol 0 I think these are all wired interrupts, and maybe IRQ==GSI (?), and I think the ACPI link devices are configurable connections between an INTx and the IOAPIC, but it's kind of hard to connect them all together. This from an arm64 system is even more obscure to me: NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0 GICv3: 256 SPIs implemented Root IRQ handler: gic_handle_irq GICv3: GICv3 features: 16 PPIs kvm [1]: vgic interrupt IRQ18 xhci-hcd xhci-hcd.0.auto: irq 67, io mem 0xfe800000 I have no clue where irq 67 goes. Maybe there's no useful way to log anything here, I dunno; it just occurred to me when looking at Jiri's series to reduce the number of irqdomain interfaces. PCI controller drivers do a lot of interrupt domain setup, and if that were more visible/concrete in dmesg, I think I might understand it better. Bjorn