From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH] arch: configuration, deleting 'CONFIG_BUG' since always need it. Date: Thu, 23 May 2013 14:09:02 +0200 Message-ID: <201305231409.02359.arnd@arndb.de> References: <519DCBEF.3090208@asianux.com> <201305231259.43750.arnd@arndb.de> <20130523112401.GO18614@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130523112401.GO18614-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: uclinux-dist-devel-bounces-ZG0+EudsQA8dtHy/vicBwGD2FQJk+8+b@public.gmane.org Errors-To: uclinux-dist-devel-bounces-ZG0+EudsQA8dtHy/vicBwGD2FQJk+8+b@public.gmane.org To: Russell King - ARM Linux Cc: Linux-sh list , Catalin Marinas , Benjamin Herrenschmidt , Chen Gang , Heiko Carstens , "paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org" , "H. Peter Anvin" , Michel Lespinasse , Hans-Christian Egtvedt , Linux-Arch , linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Yoshinori Sato , Richard Weinberger , Helge Deller , the arch/x86 maintainers , "James E.J. Bottomley" , "mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org" , Geert Uytterhoeven , Frederic Weisbecker List-Id: linux-arch.vger.kernel.org On Thursday 23 May 2013, Russell King - ARM Linux wrote: > This is the problem you guys are missing - unreachable() means "we lose > control of the CPU at this point". I'm absolutely aware of this. Again, the current behaviour of doing nothing at all isn't very different from undefined behavior when you get when you get to the end of a function returning a pointer without a "return" statement, or when you return from a function that has determined that it is not safe to continue. > If you have an embedded system and you've taken out all the printk() > stuff, you most certainly want the system to do something if you hit > an unexpected condition. I did not claim that it was a good idea to disable BUG(), all I said is that "random stuff may happen" is probably what Matt Mackall had in mind when he introduced the option. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Arnd Bergmann Date: Thu, 23 May 2013 14:09:02 +0200 References: <519DCBEF.3090208@asianux.com> <201305231259.43750.arnd@arndb.de> <20130523112401.GO18614@n2100.arm.linux.org.uk> In-Reply-To: <20130523112401.GO18614@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201305231409.02359.arnd@arndb.de> Subject: Re: [PATCH] arch: configuration, deleting 'CONFIG_BUG' since always need it. To: Russell King - ARM Linux Cc: Geert Uytterhoeven , Chen Gang , =?iso-8859-1?q?H=E5vard_Skinnemoen?= , Hans-Christian Egtvedt , Mike Frysinger , Yoshinori Sato , Richard Kuo , "James E.J. Bottomley" , Helge Deller , Benjamin Herrenschmidt , "paulus@samba.org" , Martin Schwidefsky , Heiko Carstens , linux390@de.ibm.com, Paul Mundt , Jeff Dike , Richard Weinberger , Thomas Gleixner , "mingo@redhat.com" , "H. Peter Anvin" , the arch/x86 maintainers , "Eric W. Biederman" , Serge Hallyn , Paul McKenney , Frederic Weisbecker , David Miller , Andrew Morton , Akinobu Mita , Catalin Marinas , Michel Lespinasse , Will Deacon , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "uclinux-dist-devel@blackfin.uclinux.org" , linux-hexagon@vger.kernel.org, Parisc List , "linuxppc-dev@lists.ozlabs.org" , linux-s390@vger.kernel.org, Linux-sh list , uml-devel , uml-user , Linux-Arch List-ID: On Thursday 23 May 2013, Russell King - ARM Linux wrote: > This is the problem you guys are missing - unreachable() means "we lose > control of the CPU at this point". I'm absolutely aware of this. Again, the current behaviour of doing nothing at all isn't very different from undefined behavior when you get when you get to the end of a function returning a pointer without a "return" statement, or when you return from a function that has determined that it is not safe to continue. > If you have an embedded system and you've taken out all the printk() > stuff, you most certainly want the system to do something if you hit > an unexpected condition. I did not claim that it was a good idea to disable BUG(), all I said is that "random stuff may happen" is probably what Matt Mackall had in mind when he introduced the option. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.17.10]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id A00E02C0099 for ; Thu, 23 May 2013 22:13:24 +1000 (EST) From: Arnd Bergmann To: "Russell King - ARM Linux" Subject: Re: [PATCH] arch: configuration, deleting 'CONFIG_BUG' since always need it. Date: Thu, 23 May 2013 14:09:02 +0200 References: <519DCBEF.3090208@asianux.com> <201305231259.43750.arnd@arndb.de> <20130523112401.GO18614@n2100.arm.linux.org.uk> In-Reply-To: <20130523112401.GO18614@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Message-Id: <201305231409.02359.arnd@arndb.de> Cc: Catalin Marinas , Linux-sh list , Chen Gang , Heiko Carstens , "paulus@samba.org" , "H. Peter Anvin" , Michel Lespinasse , Hans-Christian Egtvedt , Linux-Arch , linux-s390@vger.kernel.org, Yoshinori Sato , Richard Weinberger , Helge Deller , the arch/x86 maintainers , "James E.J. Bottomley" , "mingo@redhat.com" , Geert Uytterhoeven , Frederic Weisbecker , Paul McKenney , =?iso-8859-1?q?H=E5vard_Skinnemoen?= , Serge Hallyn , Mike Frysinger , uml-devel , Will Deacon , Jeff Dike , Akinobu Mita , uml-user , "uclinux-dist-devel@blackfin.uclinux.org" , Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" , Parisc List , "linux-kernel@vger.kernel.org" , Richard Kuo , Paul Mundt , "Eric W. Biederman" , linux-hexagon@vger.kernel.org, Martin Schwidefsky , linux390@de.ibm.com, Andrew Morton , "linuxppc-dev@lists.ozlabs.org" , David Miller List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thursday 23 May 2013, Russell King - ARM Linux wrote: > This is the problem you guys are missing - unreachable() means "we lose > control of the CPU at this point". I'm absolutely aware of this. Again, the current behaviour of doing nothing at all isn't very different from undefined behavior when you get when you get to the end of a function returning a pointer without a "return" statement, or when you return from a function that has determined that it is not safe to continue. > If you have an embedded system and you've taken out all the printk() > stuff, you most certainly want the system to do something if you hit > an unexpected condition. I did not claim that it was a good idea to disable BUG(), all I said is that "random stuff may happen" is probably what Matt Mackall had in mind when he introduced the option. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Thu, 23 May 2013 14:09:02 +0200 Subject: [PATCH] arch: configuration, deleting 'CONFIG_BUG' since always need it. In-Reply-To: <20130523112401.GO18614@n2100.arm.linux.org.uk> References: <519DCBEF.3090208@asianux.com> <201305231259.43750.arnd@arndb.de> <20130523112401.GO18614@n2100.arm.linux.org.uk> Message-ID: <201305231409.02359.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thursday 23 May 2013, Russell King - ARM Linux wrote: > This is the problem you guys are missing - unreachable() means "we lose > control of the CPU at this point". I'm absolutely aware of this. Again, the current behaviour of doing nothing at all isn't very different from undefined behavior when you get when you get to the end of a function returning a pointer without a "return" statement, or when you return from a function that has determined that it is not safe to continue. > If you have an embedded system and you've taken out all the printk() > stuff, you most certainly want the system to do something if you hit > an unexpected condition. I did not claim that it was a good idea to disable BUG(), all I said is that "random stuff may happen" is probably what Matt Mackall had in mind when he introduced the option. Arnd