Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754826AbaD1XvV (ORCPT ); Mon, 28 Apr 2014 19:51:21 -0400 Received: from mail-vc0-f175.google.com ([209.85.220.175]:58010 "EHLO mail-vc0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752062AbaD1XvT (ORCPT ); Mon, 28 Apr 2014 19:51:19 -0400 MIME-Version: 1.0 In-Reply-To: <1398711006-14943-1-git-send-email-marc.zyngier@arm.com> References: <1398711006-14943-1-git-send-email-marc.zyngier@arm.com> Date: Mon, 28 Apr 2014 18:51:18 -0500 Message-ID: Subject: Re: [PATCH] arm64: fixmap: fix missing sub-page offset for earlyprintk From: Rob Herring To: Marc Zyngier Cc: "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Catalin Marinas , Will Deacon , Mark Salter Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 28, 2014 at 1:50 PM, Marc Zyngier wrote: > Commit d57c33c5daa4 (add generic fixmap.h) added (among other > similar things) set_fixmap_io to deal with early ioremap of devices. > > More recently, commit bf4b558eba92 (arm64: add early_ioremap support) > converted the arm64 earlyprintk to use set_fixmap_io. A side effect of > this conversion is that my virtual machines have stopped booting when > I pass "earlyprintk=uart8250-8bit,0x3f8" to the guest kernel. > > Turns out that the new earlyprintk code doesn't care at all about > sub-page offsets, and just assumes that the earlyprintk device will > be page-aligned. Obviously, that doesn't play well with the above example. > > Further investigation shows that set_fixmap_io uses __set_fixmap instead > of __set_fixmap_offset. A fix is to introduce a set_fixmap_offset_io that > uses the latter, and to remove the superflous call to fix_to_virt > (which only returns the value that set_fixmap_io has already given us). > > With this applied, my VMs are back in business. Tested on a Cortex-A57 > platform with kvmtool as platform emulation. > > Cc: Mark Salter > Cc: Catalin Marinas > Cc: Will Deacon > Signed-off-by: Marc Zyngier > --- > arch/arm64/kernel/early_printk.c | 6 ++---- > include/asm-generic/fixmap.h | 3 +++ > 2 files changed, 5 insertions(+), 4 deletions(-) This will be fixed already in 3.16 with my earlycon series[1] if this is not taken for 3.15. Probably still a good addition for fixmap. Rob [1] https://lkml.org/lkml/2014/4/18/573 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/