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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 A00C8C4363D for ; Wed, 30 Sep 2020 21:39:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C61E20739 for ; Wed, 30 Sep 2020 21:39:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730031AbgI3Vjb (ORCPT ); Wed, 30 Sep 2020 17:39:31 -0400 Received: from [157.25.102.26] ([157.25.102.26]:36334 "EHLO orcam.me.uk" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1725814AbgI3Vjb (ORCPT ); Wed, 30 Sep 2020 17:39:31 -0400 X-Greylist: delayed 589 seconds by postgrey-1.27 at vger.kernel.org; Wed, 30 Sep 2020 17:39:30 EDT Received: from bugs.linux-mips.org (eddie.linux-mips.org [IPv6:2a01:4f8:201:92aa::3]) by orcam.me.uk (Postfix) with ESMTPS id ED5F42BE086; Wed, 30 Sep 2020 22:29:39 +0100 (BST) Date: Wed, 30 Sep 2020 22:29:36 +0100 (BST) From: "Maciej W. Rozycki" To: Adam Borowski cc: Pavel Machek , Linus Torvalds , Randy Dunlap , LKML , "linux-doc@vger.kernel.org" , Greg Kroah-Hartman , Daniel Vetter , Yuan Ming , Willy Tarreau , Bartlomiej Zolnierkiewicz , NopNop Nop , =?UTF-8?B?5byg5LqR5rW3?= , Andy Lutomirski Subject: Re: fbcon: remove soft scrollback code (missing Doc. patch) In-Reply-To: <20200918102750.GA27828@angband.pl> Message-ID: References: <20200916205434.GA10389@duo.ucw.cz> <20200918102750.GA27828@angband.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Fri, 18 Sep 2020, Adam Borowski wrote: > > > Note that scrollback hasn't actually gone away entirely - the original > > > scrollback supported by _hardware_ still exists. > > > > > > Of course, that's really just the old-fashioned text VGA console, but > > > that one actually scrolls not by moving any bytes around, but by > > > moving the screen start address. And the scrollback similarly isn't > > > about any software buffering, but about the ability of moving back > > > that screen start address. > > > Could we pause this madness? Scrollback is still useful. I needed it > > today... it was too small, so command results I was looking for > > already scrolled away, but... life will be really painful with 0 scrollback. > > > > You'll need it, too... as soon as you get oops and will want to see > > errors just prior to that oops. > > I concur -- this a serious usability regression for regular users. Linus: > you have a serial cable on your main dev machine, so do I, but hardly any > regular people do -- that's restricted to mostly IPMI and such. > > And without some kind of scrollback, there's no way of knowing why eg. > your rootfs failed to mount (there was some oops, but its reason was at > the beginning...). Or, any other problem the user would be able to solve, > or pass the error messages to someone more knowledgeable. > > I also wonder why did you choose to remove softscrollback which is actually > useful, yet leave hardscrollback which doesn't come to use on any > non-ancient hardware: > * on !x86 there's no vgacon at all > * on x86, in-tree drivers for GPUs by Intel, nVidia and AMD (others are > dead) default to switching away from vgacon > * EFI wants its own earlycon > ... thus, the only niche left is nVidia proprietary drivers which, the last > time I looked, still used CGA text mode. For the record I keep using the console scrollback all the time, and FWIW I have gone through all the hoops required to keep using VGA hardware emulation and its console text mode with my most recent laptop, which is a ThinkPad P51; no longer manufactured, but still hardly an obsolete device by today's standards I believe. Sadly this video adapter setup has its shortcomings which used not to be there with my older hardware, which I find a functional regression to be blamed on the manufacturer, but I have learnt to live with that as I found no alternative I would find comfortable to work with. So no, it's not that nobody uses that stuff anymore, and not with obsolete hardware either. Maciej