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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 1D1D8C7618B for ; Fri, 26 Jul 2019 08:41:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6343229F3 for ; Fri, 26 Jul 2019 08:41:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564130492; bh=u9hE5TPAuhfE3I5+DNmN/ANWL4HwopSUkPDD7JGenyM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=jDWTVVDlMrhE5/vM1IcQHtI0fSu943w+ybDQEoUIg0BLFWFS2db7m18vKl4AdYM9d v2oPYrYzCQjC+8e1yNIQ2qg/H5bHAO6t1ZwfKNNogwUXRj425ESddFBnCkM7SoX1UO 9C9QboM97qtDPRjxdyE3pY8Z4iYyG1W1OOjrUUk8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725872AbfGZIlb (ORCPT ); Fri, 26 Jul 2019 04:41:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:53438 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725955AbfGZIlb (ORCPT ); Fri, 26 Jul 2019 04:41:31 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6EBFF2166E; Fri, 26 Jul 2019 08:41:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564130489; bh=u9hE5TPAuhfE3I5+DNmN/ANWL4HwopSUkPDD7JGenyM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AqDr367cELkWdsKg7/xTTW+mMoF2lxvrD+4VoeryF+ymEc4dncJKYUB9VHdcnJtWw 6HGs9KVD2otlVWphduu3Ov2QGZCNwZlvcsGOuBEMGgyWtRnFLrHgnJBsPBZabMwz5y W0IhqbTPXTMFAIkB+5ESIEvgjDm5JsljlEJbSU2M= Date: Fri, 26 Jul 2019 10:41:27 +0200 From: Greg Kroah-Hartman To: Sai Prakash Ranjan Cc: Geert Uytterhoeven , Mathieu Poirier , Suzuki K Poulose , Leo Yan , linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [Regression] Missing device nodes for ETR, ETF and STM after CONFIG_UEVENT_HELPER=n Message-ID: <20190726084127.GA28470@kroah.com> References: <20190726070429.GA15714@kroah.com> <165028a7-ff12-dd28-cc4c-57a3961dbb40@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <165028a7-ff12-dd28-cc4c-57a3961dbb40@codeaurora.org> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Fri, Jul 26, 2019 at 01:50:27PM +0530, Sai Prakash Ranjan wrote: > On 7/26/2019 12:34 PM, Greg Kroah-Hartman wrote: > > On Fri, Jul 26, 2019 at 11:49:19AM +0530, Sai Prakash Ranjan wrote: > > > Hi, > > > > > > When trying to test my coresight patches, I found that etr,etf and stm > > > device nodes are missing from /dev. > > > > I have no idea what those device nodes are. > > > > > Bisection gives this as the bad commit. > > > > > > 1be01d4a57142ded23bdb9e0c8d9369e693b26cc is the first bad commit > > > commit 1be01d4a57142ded23bdb9e0c8d9369e693b26cc > > > Author: Geert Uytterhoeven > > > Date: Thu Mar 14 12:13:50 2019 +0100 > > > > > > driver: base: Disable CONFIG_UEVENT_HELPER by default > > > > > > Since commit 7934779a69f1184f ("Driver-Core: disable /sbin/hotplug by > > > default"), the help text for the /sbin/hotplug fork-bomb says > > > "This should not be used today [...] creates a high system load, or > > > [...] out-of-memory situations during bootup". The rationale for this > > > was that no recent mainstream system used this anymore (in 2010!). > > > > > > A few years later, the complete uevent helper support was made optional > > > in commit 86d56134f1b67d0c ("kobject: Make support for uevent_helper > > > optional."). However, if was still left enabled by default, to support > > > ancient userland. > > > > > > Time passed by, and nothing should use this anymore, so it can be > > > disabled by default. > > > > > > Signed-off-by: Geert Uytterhoeven > > > Signed-off-by: Greg Kroah-Hartman > > > > > > drivers/base/Kconfig | 1 - > > > 1 file changed, 1 deletion(-) > > > > > > > > > Any idea on this? > > > > That means that who ever created those device nodes is relying on udev > > to do this, and is not doing the correct thing within the kernel and > > using devtmpfs. > > > > Any pointers to where in the kernel those devices are trying to be > > created? > > > > Somewhere in drivers/hwtracing/coresight/* probably. I am not sure, > Mathieu/Suzuki would be able to point you to the exact code. > > Also just to add on some more details, I am using *initramfs* Are you using devtmpfs for your /dev/ mount? If you enable this option, what does: ls -l /dev/etr ls -l /dev/etf ls -l /dev/stm result in? What are these device nodes for? Are they symlinks? Real devices that show up in /sys/dev/char/ as a real value? Or something else? Do you have udev rules that create these nodes somehow? thanks, greg k-h