From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Date: Sun, 1 Feb 2015 21:48:46 +0100 Subject: [Buildroot] target options for Cortex A8/A9 In-Reply-To: <8F194C039449403C9E9AFFB360BCF394@JohanW7> References: <8F194C039449403C9E9AFFB360BCF394@JohanW7> Message-ID: <20150201214846.52ebad82@free-electrons.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Dear Sagaert Johan, On Sun, 1 Feb 2015 20:51:48 +0100, Sagaert Johan wrote: > I am using imx53, this cpu has according to the datasheet an NEON SIMD media accelerator > and an VFPv3 co-processor. > So I would assume the same selections options as for the A9. > I was wondering what makes the target options different for A8 vs A9. > > I would think that for the imx53 it sould be the same as for the A9, > That is an NEON SIMD extension and a vfpv3 floating point engine. > Please clarify, it is a bit confusing to me. > > For the A8 I can select vfpv3 OR Neon, but not vfpv3 WITH NEON extension. On Cortex-A8, NEON is mandatory. On Cortex-A9, NEON is optional. So when you activate Cortex-A8, Buildroot knows NEON is available. When you activate Cortex-A9, since NEON is optional, you have to tell Buildroot if NEON is actually available or not. See arch/Config.in.arm: config BR2_cortex_a8 bool "cortex-A8" select BR2_ARM_CPU_HAS_NEON select BR2_ARM_CPU_HAS_VFPV3 select BR2_ARM_CPU_HAS_THUMB2 select BR2_ARM_CPU_ARMV7A config BR2_cortex_a9 bool "cortex-A9" select BR2_ARM_CPU_MAYBE_HAS_NEON select BR2_ARM_CPU_MAYBE_HAS_VFPV3 select BR2_ARM_CPU_HAS_THUMB2 select BR2_ARM_CPU_ARMV7A Note the difference between BR2_ARM_CPU_HAS_NEON for Cortex-A8 and BR2_ARM_CPU_MAYBE_HAS_NEON for Cortex-A9. Best regards, Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com