From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 39CD3A85 for ; Fri, 23 Jun 2017 09:07:43 +0000 (UTC) Received: from mailout3.samsung.com (mailout3.samsung.com [203.254.224.33]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 7771E134 for ; Fri, 23 Jun 2017 09:07:42 +0000 (UTC) From: Bartlomiej Zolnierkiewicz To: Daniel Vetter Date: Fri, 23 Jun 2017 11:07:33 +0200 Message-id: <10423619.jNvHD4M0jW@amdc3058> In-reply-to: MIME-version: 1.0 Content-transfer-encoding: 7Bit Content-type: text/plain; charset="us-ascii" References: <20170619052146.GA2889@jagdpanzerIV.localdomain> Cc: "ksummit-discuss@lists.linuxfoundation.org" , Linux Fbdev development list Subject: Re: [Ksummit-discuss] [TECH TOPIC] printk redesign List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, On Thursday, June 22, 2017 03:48:34 PM Daniel Vetter wrote: > On Thu, Jun 22, 2017 at 3:42 PM, Daniel Vetter wrote: > > Tears pretty much guaranteed, and after a few hacks from Alan&me I > > concluded that the only way to fix this is to at least partially > > rewrite fbdev (a dead subsystem, so no one's volunteering), with the > > risk that you get to revert it all because someone is indeed relying > > on that super-flexible module loading order sequence. The simplest fix > > would probably be to make the entire fbdev->fbcon setup depency a > > hard-coded function call, or maybe at most a one-shot symbol_get > > attempt. > > I did once hash out a plan how to fix this with the least amount of pain: > > 1. Merge a patch to build the fbcon support into the overall fb.ko > module, so that the dynamic loading nonsense is essentially disabled, > and fbcon becomes a Kconfig/compile-time only option, no longer a > runtime-selectable thing. > > 2. Wait 1 year and pray that no one reports a regression. If you're > unlucky, try to fence them of with a runtime option to disable fbcon. > > 3. Rip out the notifier nonsense and replace it by direct function > calls. You can only do that once 1. won't be reverted anymore. > > 4. Push the console_lock donw the callchains until it's again at the > right spots, auditing all the other stuff meanwhile to make sure the > locking is still correct. > > 5. Apply your patch to make console_lock sane. > > Adding fbdev maintainers and lists just. Your plan sounds good to me. Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics