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Mon, 8 Nov 2021 13:26:21 +0000 (GMT) Received: from [9.211.99.43] (unknown [9.211.99.43]) by b03ledav003.gho.boulder.ibm.com (Postfix) with ESMTP; Mon, 8 Nov 2021 13:26:21 +0000 (GMT) Message-ID: <889a40d5-5bb7-c0cd-2ebe-849c80a2780b@linux.ibm.com> Date: Mon, 8 Nov 2021 07:26:21 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Reply-To: wschmidt@linux.ibm.com Subject: Re: lld status with powerpc64 To: Adhemerval Zanella , Fangrui Song , Tulio Magno Quites Machado Filho , Alan Modra , Nemanja Ivanovic Cc: libc-alpha@sourceware.org References: <20211026200346.3371750-1-adhemerval.zanella@linaro.org> <20211026203327.6b2o5k4cmkuzzm6j@google.com> <87lf2ejdnw.fsf@linux.ibm.com> <87ilxijd5f.fsf@linux.ibm.com> <20211105072312.wbqrhgyjvsypkj52@google.com> <35b483cc-fb4e-6770-bff2-aebb5f178614@linaro.org> <44162ce5-f791-e659-c8e5-130d3f2f694c@linaro.org> From: Bill Schmidt In-Reply-To: <44162ce5-f791-e659-c8e5-130d3f2f694c@linaro.org> Content-Type: text/plain; charset=UTF-8 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: d-bZ0Ws3N7EEvXqew-dZGdkafjAY5841 X-Proofpoint-GUID: 9WpYu2akDuH_nWv34LrXevQOtrQiEMH1 Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-08_05,2021-11-08_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 adultscore=0 clxscore=1015 mlxscore=0 lowpriorityscore=0 bulkscore=0 priorityscore=1501 spamscore=0 mlxlogscore=943 malwarescore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111080082 X-Spam-Status: No, score=-6.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, KAM_NUMSUBJECT, NICE_REPLY_A, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: Mon, 08 Nov 2021 13:26:29 -0000 On 11/8/21 5:37 AM, Adhemerval Zanella wrote: > > On 07/11/2021 11:24, Bill Schmidt wrote: >> Please coordinate with Alan Modra and Nemanja Ivanovic on this topic.  There are ongoing discussions about bfd and lld linker support around @notoc that will be resolved soon, and Tulio is on vacation, so I don't want the community to make steps they'll have to undo later, or for people to engage in duplicate work. > For this specific issue I just sent a patch to fix it on glibc side [1]. > However I think it would be good if lld also implements the ld.bfd > optimization to fallback to older stub generation if no pcrel relocation > is found (although it is debatable that @notoc should implicit generate > older ISA code depending of the resulting objects being linked against). > > [1] https://patchwork.sourceware.org/project/glibc/patch/20211108113316.8867-1-adhemerval.zanella@linaro.org/ Hi Adhemerval, Current course and speed is that @notoc will imply pcrel stubs on P10 and later, but will not do so on P9 and earlier. The relocation currently associated with @notoc actually came with ELFv2 on P8 and, although no compilers ever generated @notoc, assembly routines using it prior to P10 are a valid case and should not be punished. This can be handled by generating a different reloc for @notoc in the two cases. If this solution holds up, then changes to glibc should be unnecessary. Thanks, Bill