From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752300AbeBZIuC (ORCPT ); Mon, 26 Feb 2018 03:50:02 -0500 Received: from mail-lf0-f67.google.com ([209.85.215.67]:35929 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751563AbeBZIt6 (ORCPT ); Mon, 26 Feb 2018 03:49:58 -0500 X-Google-Smtp-Source: AG47ELvGYHIgvrr4KnUKRHG7rai7DRnLdYSbHWPnAeOUcCMCbN3uC/SopN0BDRlfP5ggqL878/7Zsw== Date: Mon, 26 Feb 2018 11:49:55 +0300 From: Cyrill Gorcunov To: "Kirill A. Shutemov" Cc: Ingo Molnar , Borislav Petkov , tglx@linutronix.de, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, willy@infradead.org, hpa@zytor.com, kirill.shutemov@linux.intel.com, peterz@infradead.org, luto@amacapital.net, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/boot] x86/boot/compressed/64: Prepare trampoline memory Message-ID: <20180226084955.GB5308@uranus.lan> References: <20180209142228.21231-4-kirill.shutemov@linux.intel.com> <20180224214818.GD29374@pd.tnic> <20180225105205.xicklkl3n5azdw2j@node.shutemov.name> <20180226073552.xabt55ukp24inut5@gmail.com> <20180226080256.j7jzuxyokx42uytd@node.shutemov.name> <20180226081533.GA5308@uranus.lan> <20180226083709.al5pvzwzyxuci4qp@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180226083709.al5pvzwzyxuci4qp@node.shutemov.name> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 26, 2018 at 11:37:09AM +0300, Kirill A. Shutemov wrote: > On Mon, Feb 26, 2018 at 11:15:34AM +0300, Cyrill Gorcunov wrote: > > On Mon, Feb 26, 2018 at 11:02:56AM +0300, Kirill A. Shutemov wrote: > > ... > > > > Also, could do a puts() hexdump of the affected memory area _before_ we overwrite > > > > it? Is it empty? Could we add some debug warning that checks that it's all zeroes? > > > > > > The problem is that we don't really have a way get a message out of there. > > > > > > http://lkml.kernel.org/r/793b9c55-e85b-97b5-c857-dd8edcda4081@zytor.com > > > > > > > I'm sorry for stepping in (since I didn't follow the series in details) > > but can't we use vga memory here and print this early data tere? > > I have no idea how to do this :/ https://wiki.osdev.org/Printing_To_Screen Kirill, note that it might not do the trick at all, just give the link a shot and check if it would worth the efforts. > > And what about systems without monitor at all? Such early boot things *require* additional equipment anyway jtag/monitors/etc for debug stage at least.