From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: start_kernel(): bug: interrupts were enabled early Date: Wed, 31 Mar 2010 14:57:20 -0700 Message-ID: <4BB3C540.9000405@zytor.com> References: <20100325194100.GA2364@debian> <20100331134048.da4e35a7.akpm@linux-foundation.org> <4BB3B4DB.7040904@kernel.org> <20100331210145.GB32165@parisc-linux.org> <4BB3B8FC.1020608@zytor.com> <20100331211754.GC32165@parisc-linux.org> <20100331215411.GB17715@flint.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from terminus.zytor.com ([198.137.202.10]:40368 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755808Ab0CaWBb (ORCPT ); Wed, 31 Mar 2010 18:01:31 -0400 In-Reply-To: <20100331215411.GB17715@flint.arm.linux.org.uk> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Christoph Lameter , Matthew Wilcox , Yinghai Lu , Andrew Morton , Rabin Vincent On 03/31/2010 02:54 PM, Russell King wrote: > On Wed, Mar 31, 2010 at 04:42:25PM -0500, Christoph Lameter wrote: >> Do not run the checks while we are in a single threaded context? >> >> I thought we had some dynamic code patching thingamy that could change >> those when we go to smp mode? > > You have to remember that on embedded architectures, such as ARM, > where XIP is supported we can't change the text segment at run time - > which means dynamic code patching won't work. > > However, the kernel should still work in such situations. > The question still remains what the incremental cost is of doing irqsave/irqrestore. -hpa From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from terminus.zytor.com ([198.137.202.10]:40368 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755808Ab0CaWBb (ORCPT ); Wed, 31 Mar 2010 18:01:31 -0400 Message-ID: <4BB3C540.9000405@zytor.com> Date: Wed, 31 Mar 2010 14:57:20 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: start_kernel(): bug: interrupts were enabled early References: <20100325194100.GA2364@debian> <20100331134048.da4e35a7.akpm@linux-foundation.org> <4BB3B4DB.7040904@kernel.org> <20100331210145.GB32165@parisc-linux.org> <4BB3B8FC.1020608@zytor.com> <20100331211754.GC32165@parisc-linux.org> <20100331215411.GB17715@flint.arm.linux.org.uk> In-Reply-To: <20100331215411.GB17715@flint.arm.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Christoph Lameter , Matthew Wilcox , Yinghai Lu , Andrew Morton , Rabin Vincent , lkml , penberg@cs.helsinki.fi, Benjamin Herrenschmidt , linux-arch@vger.kernel.org Message-ID: <20100331215720.T1aKALBopndxP_A1xcETqz-YBNqk9mpy-61sg049by8@z> On 03/31/2010 02:54 PM, Russell King wrote: > On Wed, Mar 31, 2010 at 04:42:25PM -0500, Christoph Lameter wrote: >> Do not run the checks while we are in a single threaded context? >> >> I thought we had some dynamic code patching thingamy that could change >> those when we go to smp mode? > > You have to remember that on embedded architectures, such as ARM, > where XIP is supported we can't change the text segment at run time - > which means dynamic code patching won't work. > > However, the kernel should still work in such situations. > The question still remains what the incremental cost is of doing irqsave/irqrestore. -hpa