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 0422C1A006B for ; Mon, 21 Sep 2015 20:07:32 +1000 (AEST) Subject: Re: [PATCH] powerpc: Kconfig.cputype: Disallow TUNE_CELL on LE systems To: Michael Ellerman References: <1442585820-18623-1-git-send-email-thuth@redhat.com> <1442819926.354.5.camel@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org, Benjamin Herrenschmidt , Paul Mackerras , boqun.feng@gmail.com From: Thomas Huth Message-ID: <55FFD6DF.2080300@redhat.com> Date: Mon, 21 Sep 2015 12:07:27 +0200 MIME-Version: 1.0 In-Reply-To: <1442819926.354.5.camel@ellerman.id.au> 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 21/09/15 09:18, Michael Ellerman wrote: > On Fri, 2015-09-18 at 16:17 +0200, Thomas Huth wrote: >> It looks somewhat weird that you can enable TUNE_CELL on little >> endian systems, so let's disable this option with CPU_LITTLE_ENDIAN. >> >> Signed-off-by: Thomas Huth >> --- >> I first thought that it might be better to make this option depend >> on PPC_CELL instead ... but I guess it's a bad idea to depend a >> CPU option on a platform option? Alternatively, would it make >> sense to make it depend on (GENERIC_CPU || CELL_CPU) instead? > > Hmm, it's a little backward, but I think it would be fine, and less confusing > for users. Both PS3 and Cell select PPC_CELL, so it would work in both those > cases. It's just that when you step through the kernel config (e.g. with "make menuconfig"), you normally step through the "Processor support" first, and then later do the "Platform support". I think most users won't look back into "Processor support" again once they already reached the "Platform support" section, so this TUNE_CELL option then might appear unnoticed when you enable a Cell platform under "Platform support". That's why thought that CPU_LITTLE_ENDIAN or (GENERIC_CPU || CELL_CPU) might be the better option here... but if you think PPC_CELL is the better way to go, I'm also fine to change my patch to use this instead (in the end, TUNE_CELL is likely hardly used anymore nowadays, so it should not be that bad if it does not appear "immediately" to the user). Thomas