From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by sourceware.org (Postfix) with ESMTPS id CD4BA385DC1F for ; Wed, 22 Apr 2020 19:33:56 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org CD4BA385DC1F Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 03MJXZwu126170; Wed, 22 Apr 2020 15:33:52 -0400 Received: from ppma03dal.us.ibm.com (b.bd.3ea9.ip4.static.sl-reverse.com [169.62.189.11]) by mx0a-001b2d01.pphosted.com with ESMTP id 30gmv175rk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 22 Apr 2020 15:33:52 -0400 Received: from pps.filterd (ppma03dal.us.ibm.com [127.0.0.1]) by ppma03dal.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id 03MJURrU007217; Wed, 22 Apr 2020 19:33:51 GMT Received: from b01cxnp23033.gho.pok.ibm.com (b01cxnp23033.gho.pok.ibm.com [9.57.198.28]) by ppma03dal.us.ibm.com with ESMTP id 30fs674r3k-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 22 Apr 2020 19:33:51 +0000 Received: from b01ledav005.gho.pok.ibm.com (b01ledav005.gho.pok.ibm.com [9.57.199.110]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 03MJXpNk41025924 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 22 Apr 2020 19:33:51 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E2808AE062; Wed, 22 Apr 2020 19:33:50 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A6CF2AE05C; Wed, 22 Apr 2020 19:33:50 +0000 (GMT) Received: from [9.85.144.164] (unknown [9.85.144.164]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 22 Apr 2020 19:33:50 +0000 (GMT) Subject: Re: [PATCH v3 3/6] powerpc64le: raise GCC requirement to 7.4 for long double transition To: Florian Weimer , "Paul E. Murphy via Libc-alpha" References: <87lfmnim4v.fsf@mid.deneb.enyo.de> From: Paul E Murphy Message-ID: Date: Wed, 22 Apr 2020 14:33:50 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <87lfmnim4v.fsf@mid.deneb.enyo.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-22_06:2020-04-22, 2020-04-22 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 adultscore=0 malwarescore=0 suspectscore=0 phishscore=0 spamscore=0 bulkscore=0 mlxlogscore=999 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004220147 X-Spam-Status: No, score=-21.7 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_DMARC_STATUS, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Apr 2020 19:33:58 -0000 On 4/22/20 10:19 AM, Florian Weimer wrote: > * Paul E. Murphy via Libc-alpha: > >> diff --git a/manual/install.texi b/manual/install.texi >> index 71bf47cac6..66de8ea59b 100644 >> --- a/manual/install.texi >> +++ b/manual/install.texi >> @@ -507,6 +507,11 @@ the newest version of the compiler that is known to work for building >> release time, GCC 9.2.1 is the newest compiler verified to work to build >> @theglibc{}. >> >> +For PowerPC 64-bits little-endian (powerpc64le), a GCC version with >> +support for @option{-mno-gnu-attribute} is required. As of release time, >> +this means GCC 7.4 (excepting 7.5) or newer. The compiler option is required >> +for building the GNU C Library with support for IEEE long double. > > Why “excepting 7.5”? Somewhere, there should be an explanation, maybe > in a @c comment in the Texinfo sources if it's too confusing to end > users. FSF GCC 7.5 does not accept both the -mabi=* and -mlong-double-128 options being present on the command line. Ironically, it errors instructing you to pass the -mlong-double-128 option. > Also, missing two spaces at the end of sentences. > > And quick question for my understanding: Could we get the effect of > -mno-gnu-attribute using strip if we wanted? (Not that I think this > change is required, I'm fine with bumping the minimum GCC > requirement.) Yes, I think one could post-process each object file to strip the .gnu.attributes section. Though, you do highlight an impedance mismatch between the commit message and documentation regarding the -mabi requirements. How about the following instead? For PowerPC 64-bits little-endian (powerpc64le), a GCC version with support for @option{-mno-gnu-attribute}, @option{-mabi=ieeelongdouble}, and @option{-mabi=ibmlondouble} is required. Likewise, the compiler must also support passing @options{-mlong-double-128} with the preceding options. As of release, this implies GCC 7.4 and newer (excepting GCC 7.5.0, see GCC PR94200). These additional features are required for building the GNU C Library with support for IEEE long double.