From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C6C3C2BA83 for ; Thu, 13 Feb 2020 17:49:14 +0000 (UTC) Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9F7A621734 for ; Thu, 13 Feb 2020 17:49:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=kroah.com header.i=@kroah.com header.b="fGv75EtI"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="F/2x1RHi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F7A621734 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kroah.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernelnewbies-bounces@kernelnewbies.org Received: from localhost ([::1] helo=shelob.surriel.com) by shelob.surriel.com with esmtp (Exim 4.92.3) (envelope-from ) id 1j2Ibh-0003Su-BJ; Thu, 13 Feb 2020 12:48:57 -0500 Received: from new3-smtp.messagingengine.com ([66.111.4.229]) by shelob.surriel.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.3) (envelope-from ) id 1j2Ibf-0003Sn-7i for Kernelnewbies@kernelnewbies.org; Thu, 13 Feb 2020 12:48:55 -0500 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailnew.nyi.internal (Postfix) with ESMTP id 3FC004BD6; Thu, 13 Feb 2020 12:48:52 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Thu, 13 Feb 2020 12:48:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm3; bh=EbysV8NEs+MVlY9oNbmhpNy2xBP cjrg7aPJrpq7FyQk=; b=fGv75EtIicqQ546nZlRrBJspQvDcltL0E/L1JCU/eCJ EndHL6Of8WryB8Ew8J1L0nycqrIH1ExEL7J8MBIkezHILieiW1i1K8OCxhKn4z9G cNIldwuBK4wv8t4wNeqAOkK3NDGCor3AcdzCyx7Qg8EZA5cRhuaIhZAq8YLoY+ji lk9TbKFQ2Meht3Xm2djjzFKhbcoNZ4ttLMD0oxQPmH34tr/8Y4DR7Dewv8LSx693 YjQWdJW5C3egCXP6OsNfv99mjSjtdd9jpUJJVQmMXbu4iUx9MC6yNmPYvlcahaCq 8viXJUJWH1omjVS6+2mrSoz9YupX03wR1fBYU+HGgVg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=EbysV8 NEs+MVlY9oNbmhpNy2xBPcjrg7aPJrpq7FyQk=; b=F/2x1RHikGGFPXM5DC2wMn bGF8wNrZ1xWaOvYA+HojMNvhIxqaYF2rfKyCncc+ssnx8OixH+//uW71GdxsUGbA WWA2myR/aq86XChdDgQeR93ym1dI9xo0+LRovFLKJNzNRm9sSozvy7pbWTju2Sl4 QO/KZgZyNi7+HN5BpmzPEUcwg46Pe5dETfu6ukYkg9v8oyevams8GIAoRTHNLmBj CiJqbRzzKdOBKCEVm8yDpA2ZemvprD6ENnAsUN2rf9G1tAlEAnOI45dCgPDzPOYK a0A6gUvIpNIKHnZR/w2h+CctfXkiUmwRsQqUB62M0A6kwBWP44KHiJBasLHCUWdQ == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrieekgddutdeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne goufhprghmkfhpqdhouhhtucdlhedttddmnecujfgurhepfffhvffukfhfgggtuggjseht tdertddttddvnecuhfhrohhmpefirhgvghcumffjuceoghhrvghgsehkrhhorghhrdgtoh hmqeenucfkphepuddtgedrudefvddruddruddtgeenucevlhhushhtvghrufhiiigvpedt necurfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Received: from localhost (unknown [104.132.1.104]) by mail.messagingengine.com (Postfix) with ESMTPA id 4C3D53280066; Thu, 13 Feb 2020 12:48:47 -0500 (EST) Date: Thu, 13 Feb 2020 09:48:46 -0800 From: Greg KH To: Sadanand Warrier Subject: Re: PCIe hotplug Message-ID: <20200213174846.GA3688355@kroah.com> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: Kernelnewbies@kernelnewbies.org X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kernelnewbies-bounces@kernelnewbies.org On Thu, Feb 13, 2020 at 12:40:59PM -0500, Sadanand Warrier wrote: > Hi > I had question about PCIe hotplug. We have hardware that is connected > to the host by means of two PCIe switches. i.e. the host sees a PCIe switch > connected to one of its buses and on the far side of that switch another > PCIe switch which has a PCIe device. > It is possible that this device does not train its host facing PCIe > links before the server enumerates down its PCI bus and reaches those > links. It is also possible the PCIe switch to which the device is attached > has not been able to train its own links before server enumeration. > Is PCIe hotplug built to work on schemes like this? Let us assume that > the hardware has been designed to trasmit a presence signal once the links > are trained but this could happen after the server enumeration? Look at the PCIe hotplug spec, it should answer all of your questions about this. > Incidentally does the server take advantage of the BIOS/UEFI enumeration? Yes, of course, how else would the kernel be able to enumerate PCI devices? :) thanks, greg k-h _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies