From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f46.google.com (mail-pa0-f46.google.com [209.85.220.46]) by dpdk.org (Postfix) with ESMTP id 4997C8E5A for ; Fri, 2 Oct 2015 03:21:22 +0200 (CEST) Received: by pacfv12 with SMTP id fv12so92742488pac.2 for ; Thu, 01 Oct 2015 18:21:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:to:references:cc:from:message-id:date:user-agent :mime-version:in-reply-to:content-type:content-transfer-encoding; bh=jbJlcx8E022zkQdpoEZI3dexpyVb7RcZdxtyvbfumzQ=; b=Aq4lr+lmpYC5sj0/pK1DhAO/cA8d1UUeQpW6BHW3+Kp2HoWgciTmR4N+U5UxfJyzTI OvIb1xV5U66JfQ0h3J/DIJ65+CZr3vAz/ahvn8egXnMNpbhYAZPXsUP2UQFd1VfPsHp7 zl9/jEmZQG+i1+13K2ZUR0pTEQUisbyBn6LfqV7Tt3bFp9HUjgZ3r6uq6EiocMS6vKh/ BFttk/ILhXwOxHza2AXPSByIfnTmGtwf/fKeg+QMmElVacEhO4186jCVdRntJ+iyqJBT EexkXw9YMISS3DAyAfv9MuzYsr/n6BYbwV1557D3OduGKgdB4IKC0a7RPRriEWoeH9bw ToGw== X-Received: by 10.68.232.162 with SMTP id tp2mr15571831pbc.162.1443748881590; Thu, 01 Oct 2015 18:21:21 -0700 (PDT) Received: from [192.168.1.188] (static-50-53-21-5.bvtn.or.frontiernet.net. [50.53.21.5]) by smtp.googlemail.com with ESMTPSA id rb8sm9134590pab.14.2015.10.01.18.21.20 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Oct 2015 18:21:20 -0700 (PDT) To: Stephen Hemminger References: <1443652138-31782-1-git-send-email-stephen@networkplumber.org> <1443652138-31782-3-git-send-email-stephen@networkplumber.org> <560DC45A.3050507@gmail.com> <20151001170145.4239de9f@urahara> From: Alexander Duyck Message-ID: <560DDC0F.80302@gmail.com> Date: Thu, 1 Oct 2015 18:21:19 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <20151001170145.4239de9f@urahara> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: dev@dpdk.org, hjk@hansjkoch.de, gregkh@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [dpdk-dev] [PATCH 2/2] uio: new driver to support PCI MSI-X X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 02 Oct 2015 01:21:22 -0000 On 10/01/2015 05:01 PM, Stephen Hemminger wrote: > On Thu, 1 Oct 2015 16:40:10 -0700 > Alexander Duyck wrote: > >> I agree with some other reviewers. Why call pci_enable_msix in open? >> It seems like it would make much more sense to do this on probe, and >> then disable MSI-X on free. I can only assume you are trying to do it >> to save on resources but the fact is this is a driver you have to >> explicitly force onto a device so you would probably be safe to assume >> that they plan to use it in the near future. > Because if interface is not up, the MSI handle doesn't have to be open. > This saves resources and avoids some races. Yes, but it makes things a bit messier for the interrupts. Most drivers take care of interrupts during probe so that if there are any allocation problems they can take care of them then instead of leaving an interface out that will later fail when it is brought up. It ends up being a way to deal with the whole MSI-X fall-back issue. - Alex