Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753042Ab1DUTKo (ORCPT ); Thu, 21 Apr 2011 15:10:44 -0400 Received: from palinux.external.hp.com ([192.25.206.14]:56940 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752376Ab1DUTKn (ORCPT ); Thu, 21 Apr 2011 15:10:43 -0400 Date: Thu, 21 Apr 2011 13:10:41 -0600 From: Matthew Wilcox To: Neil Horman Cc: linux-kernel@vger.kernel.org, Jesse Barnes , linux-pci@vger.kernel.org Subject: Re: [PATCH] pci: Export pci device msi table via sysfs Message-ID: <20110421191041.GE31296@parisc-linux.org> References: <1303412267-1948-1-git-send-email-nhorman@tuxdriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1303412267-1948-1-git-send-email-nhorman@tuxdriver.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1557 Lines: 42 On Thu, Apr 21, 2011 at 02:57:47PM -0400, Neil Horman wrote: > b) msi_table - populated only if msi(x) is enabled, it lists the irqs allocated > to the pci device You're not the first one to try this ... the problem is, you can easily overflow a single 4k page. A device can have up to 2k MSI-X entries, and we might take up to 5 bytes for each one, so we'd need a 10k buffer. > +#ifdef CONFIG_PCI_MSI > +static ssize_t msi_list_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct pci_dev *pdev = to_pci_dev(dev); > + struct msi_desc *entry; > + int first, last; > + ssize_t count = 0; > + > + if (!(pdev->msi_enabled || pdev->msix_enabled)) > + return 0; > + > + list_for_each_entry(entry, &pdev->msi_list, list) > + count += sprintf(&buf[count], "%d ", entry->irq); > + > + return count; > +} > +#endif The fundamental problem is that the way Linux uses MSI-X is completely bollocks. I've got a few hours to myself on a plane coming up in six weeks, and I hope to rewrite it then (I've already written my talk, so what else am I going to do? :-) -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/