From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3rPlsy69nlzDqGn for ; Wed, 8 Jun 2016 21:03:34 +1000 (AEST) Subject: Re: [PATCH] powerpc: Fix IBM_ARCH_VEC_NRCORES_OFFSET value To: Benjamin Herrenschmidt , Michael Ellerman References: <1465339861.3263.24.camel@kernel.crashing.org> Cc: linuxppc dev list , Balbir Singh From: Thomas Huth Message-ID: <5757FB81.7040905@redhat.com> Date: Wed, 8 Jun 2016 13:03:29 +0200 MIME-Version: 1.0 In-Reply-To: <1465339861.3263.24.camel@kernel.crashing.org> Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 08.06.2016 00:51, Benjamin Herrenschmidt wrote: > Commit 7cc851039d643a2ee7df4d18177150f2c3a484f5 > "powerpc/pseries: Add POWER8NVL support to ibm,client-architecture-support call" > introduced a regression by adding fields to the beginning of the > ibm_architecture_vec structure without updating IBM_ARCH_VEC_NRCORES_OFFSET. > > This causes the kernel to print a warning at boot and to fail to adjust > the number of cores based on the number of threads before doing the CAS > call to firmware. > > This is quite a fragile piece of code sadly, we should try to find a way > to avoid that hard coded offset at some point, but for now this fixes it. > > Signed-off-by: Benjamin Herrenschmidt > --- > > diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c > index ccd2037..6ee4b72 100644 > --- a/arch/powerpc/kernel/prom_init.c > +++ b/arch/powerpc/kernel/prom_init.c > @@ -719,7 +719,7 @@ unsigned char ibm_architecture_vec[] = { > * must match by the macro below. Update the definition if > * the structure layout changes. > */ > -#define IBM_ARCH_VEC_NRCORES_OFFSET 125 > +#define IBM_ARCH_VEC_NRCORES_OFFSET 133 > W(NR_CPUS), /* number of cores supported */ > 0, > 0, Yes, that should be the right offset now! Please also add "Cc: stable@vger.kernel.org # v4.0+" to the patch since the commit 7cc851039d64 did have that as well. And sorry for breaking this! Reviewed-by: Thomas Huth