From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guo Ren Subject: Re: [PATCH 15/19] csky: Build infrastructure Date: Wed, 28 Mar 2018 16:04:53 +0800 Message-ID: <20180328080452.GA12230@guoren> References: <20180320131342.GA31542@guoren> <20180321124137.GA21320@guoren> <20180327023927.GA11454@guoren> <20180328034957.GA4482@guoren> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann Cc: linux-arch , Linux Kernel Mailing List , Thomas Gleixner , Daniel Lezcano , Jason Cooper , c-sky_gcc_upstream@c-sky.com, gnu-csky@mentor.com, thomas.petazzoni@bootlin.com, wbx@uclibc-ng.org List-Id: linux-arch.vger.kernel.org Hi Arnd, On Wed, Mar 28, 2018 at 09:40:49AM +0200, Arnd Bergmann wrote: > Ok, thanks for the clarification. Obviously if they are mutually incompatible, > there is no point in using a common kernel, so your current version is > absolutely fine, and this is similar to how we cannot have a common kernel > between ARMv5, ARMv7-A and ARMv7-M, which are all incompatible > at the kernel level. Yes. > One more question for my understanding: Are the three types of ck8xx > CPUs mutually incompatible in user space as well, or are the differences > only for the kernel? For the ARM example, ARMv5 and ARMv7 > fundamentally require separate kernels, but both can run user space > programs built for ARMv5. -mcpu=ck807 app could run on ck807, ck810, ck860. -mcpu=ck810 app could run on ck807, ck810, ck860. -mcpu=ck860 app only run on ck860. They are all incompatible at the kernel level. Best Regards Guo Ren From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp2200-217.mail.aliyun.com ([121.197.200.217]:46873 "EHLO smtp2200-217.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750829AbeC1IFZ (ORCPT ); Wed, 28 Mar 2018 04:05:25 -0400 Date: Wed, 28 Mar 2018 16:04:53 +0800 From: Guo Ren Subject: Re: [PATCH 15/19] csky: Build infrastructure Message-ID: <20180328080452.GA12230@guoren> References: <20180320131342.GA31542@guoren> <20180321124137.GA21320@guoren> <20180327023927.GA11454@guoren> <20180328034957.GA4482@guoren> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Arnd Bergmann Cc: linux-arch , Linux Kernel Mailing List , Thomas Gleixner , Daniel Lezcano , Jason Cooper , c-sky_gcc_upstream@c-sky.com, gnu-csky@mentor.com, thomas.petazzoni@bootlin.com, wbx@uclibc-ng.org Message-ID: <20180328080453.b7FKfRyinMLdR1eLDKSOe7YclF07ZzzNUKKMzSUmUac@z> Hi Arnd, On Wed, Mar 28, 2018 at 09:40:49AM +0200, Arnd Bergmann wrote: > Ok, thanks for the clarification. Obviously if they are mutually incompatible, > there is no point in using a common kernel, so your current version is > absolutely fine, and this is similar to how we cannot have a common kernel > between ARMv5, ARMv7-A and ARMv7-M, which are all incompatible > at the kernel level. Yes. > One more question for my understanding: Are the three types of ck8xx > CPUs mutually incompatible in user space as well, or are the differences > only for the kernel? For the ARM example, ARMv5 and ARMv7 > fundamentally require separate kernels, but both can run user space > programs built for ARMv5. -mcpu=ck807 app could run on ck807, ck810, ck860. -mcpu=ck810 app could run on ck807, ck810, ck860. -mcpu=ck860 app only run on ck860. They are all incompatible at the kernel level. Best Regards Guo Ren