From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH RFC 5/7] xen: arm: rewrite start of day page table and cpu bring up Date: Wed, 18 Sep 2013 18:06:21 +0100 Message-ID: <5239DD8D.8090001@linaro.org> References: <1379381846.11304.73.camel@hastur.hellion.org.uk> <1379382050-11821-5-git-send-email-ian.campbell@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1379382050-11821-5-git-send-email-ian.campbell@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell Cc: julien.grall@citrix.com, stefano.stabellini@eu.citrix.com, tim@xen.org, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 09/17/2013 02:40 AM, Ian Campbell wrote: > diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S > index b8334e2..abaacfd 100644 > --- a/xen/arch/arm/arm32/head.S > +++ b/xen/arch/arm/arm32/head.S > @@ -37,6 +37,25 @@ [..] > + > +common_start: > + mov r7, #0 /* r13 := CPU ID */ > + mrc CP32(r1, MPIDR) > + tst r1, #(1<<31) /* Multiprocessor extension supported? */ > + beq 1f > + tst r1, #(1<<30) /* Uniprocessor system? */ > + bne 1f > + bic r7, r1, #(0xff << 24) /* Mask out flags to get CPU ID */ Can you use #(~MPIDR_HWID_MASK) instead of #(0xff << 24)? I think, it's the same in arm64/head.S. -- Julien Grall