Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752889AbZJ1Lit (ORCPT ); Wed, 28 Oct 2009 07:38:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752670AbZJ1Lir (ORCPT ); Wed, 28 Oct 2009 07:38:47 -0400 Received: from aa002msb.fastweb.it ([85.18.95.81]:38085 "EHLO aa002msb.fastweb.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751737AbZJ1Liq (ORCPT ); Wed, 28 Oct 2009 07:38:46 -0400 Message-ID: <4AE82D17.6040900@evidence.eu.com> Date: Wed, 28 Oct 2009 12:37:59 +0100 From: Claudio Scordino User-Agent: Thunderbird 2.0.0.23 (X11/20090817) MIME-Version: 1.0 To: Catalin Marinas CC: linux-kernel@vger.kernel.org, rmk+kernel@arm.linux.org.uk, linux-arm-kernel@lists.arm.linux.org.uk, akpm@linux-foundation.org Subject: Re: [PATCH][RE-SUBMIT] Default setting of the ARM_UNWIND option References: <4AD73DA4.4050006@evidence.eu.com> <1255620333.10164.77.camel@pc1117.cambridge.arm.com> <4AE55D83.7080608@evidence.eu.com> <1256555452.5282.21.camel@pc1117.cambridge.arm.com> In-Reply-To: <1256555452.5282.21.camel@pc1117.cambridge.arm.com> Content-Type: multipart/mixed; boundary="------------040300070102060505080405" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3304 Lines: 93 This is a multi-part message in MIME format. --------------040300070102060505080405 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Catalin Marinas ha scritto: > On Mon, 2009-10-26 at 09:27 +0100, Claudio Scordino wrote: > >> My ARM board hanged at the initial "Calibrating delay loop" message. >> >> After some inspection, I found out the problem to be with commit >> adf8b37bafc1495393201a2ae4235846371870d0. This commit introduces stack >> unwinding for ARM, and set it enabled by default. However, it seems to >> not work with buggy or not-EABI compilers. >> >> My suggestion is to keep the feature (which is fine) but change the >> default setting of the option (see the attached patch). >> > > The option still depends on EXPERIMENTAL, so you get ARM_UNWIND on when > enabling that. > > I'm more in favour of a #warning on #error in the unwind.c file based on > the compiler version rather than not having it on by default. The reason > is that people reported performance improvements when compiling the > kernel without frame pointers. > [Sorry, I sent the wrong patch... This is the new one.] This solution is fine too (even if I still think that changing the default setting is better). Please, consider the patch in attachment: is it like you would have it ? BTW, do we have any list of buggy or not-EABI versions of the gcc compiler ? Many thanks, Claudio --------------040300070102060505080405 Content-Type: text/x-patch; name="0001-Some-warnings-when-compiling-ARM-unwind-support-with.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename*0="0001-Some-warnings-when-compiling-ARM-unwind-support-with.pa"; filename*1="tch" From: Claudio Scordino Date: Mon, 26 Oct 2009 17:13:18 +0100 Subject: [PATCH 1/1] Some warnings when compiling ARM unwind support with a buggy or not-EABI compiler. ARM unwind support is known to build only with EABI and not-buggy compilers. Now we check the compiler and raise a #warning in case of wrong compiler. Signed-off-by: Claudio Scordino --- arch/arm/kernel/unwind.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c index 39baf11..47345c1 100644 --- a/arch/arm/kernel/unwind.c +++ b/arch/arm/kernel/unwind.c @@ -26,6 +26,15 @@ * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html */ +#if !defined (__ARM_EABI__) +#warning Your compiler does not have EABI support. +#warning ARM unwind support it is known to compile only on EABI compilers. +#warning Change compiler or disable ARM_UNWIND option. +#elif (__GNUC__ == 4 && __GNUC_MINOR__ == 2) +#warning Your compiler is too buggy; it is known to not compile ARM unwind support. +#warning Change compiler or disable ARM_UNWIND option. +#endif + #include #include #include -- 1.6.0.4 --------------040300070102060505080405-- -- 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/