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Rao" Subject: Re: [PATCH 0/4] powerpc/64: ELFv2 conversion To: Christophe Leroy , "linuxppc-dev@lists.ozlabs.org" , Michael Ellerman , Nicholas Piggin References: <20230505071850.228734-1-npiggin@gmail.com> <6d0609ae-e31b-8530-7509-7861b07d66c7@csgroup.eu> <87wn1n55qc.fsf@mail.lhotse> In-Reply-To: <87wn1n55qc.fsf@mail.lhotse> User-Agent: astroid/4d6b06ad (https://github.com/astroidmail/astroid) Message-Id: <1683298879.x90su0d4vv.naveen@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-GUID: GAqIRGRhrfA9UnE2-r5bvMXBMi9Bg8r0 X-Proofpoint-ORIG-GUID: Fiyw75pAsCjZ1gXUVtxGdPkcTECtVsI4 Content-Transfer-Encoding: quoted-printable X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-05-05_22,2023-05-05_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 phishscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 mlxscore=0 malwarescore=0 spamscore=0 suspectscore=0 impostorscore=0 mlxlogscore=847 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303200000 definitions=main-2305050126 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Michael Ellerman wrote: > Christophe Leroy writes: >> Le 05/05/2023 =C3=A0 09:18, Nicholas Piggin a =C3=A9crit=C2=A0: >>> This series has the steps to remove ELFv1 from the kernel build. >>> Patch 1 is a build fix, 2 defaults everything to ELFv2, 3 is >>> really a separate issue that concerns userspace. 4 removes v1 >>> support. Super glad to see this! >> >> I see CONFIG_MPROFILE_KERNEL is restricted to LITTLE_ENDIAN. Is that=20 >> correct ? Don't we have mprofile_kernel as well on BIG ENDIAN once=20 >> switched to ABI v2 ? If so, can we drop the -pg based profiling=20 >> completely, or is CLANG still not supporting mprofile_kernel ? >=20 > Clang does not support -mprofile-kernel. >=20 > AIUI they would like us to switch to -fpatchable-function-entry which > could then be supported on GCC & clang. >=20 > That would be a nice cleanup but also a bunch of work that no one has > found time to do. >=20 > https://github.com/linuxppc/issues/issues/447 > https://github.com/llvm/llvm-project/issues/57031 GCC's support for -fpatchable-function-entry needed fixes for ABIv2,=20 which have landed in the recent v13.1 release. I am looking into adding=20 support for that. >=20 >=20 > So for now we need to keep the -pg based version. Indeed, but removing elf v1 support does help cleaning up and=20 simplifying some of the tracing code. Much of the -pg code is already=20 separate, so it should be easy to drop that once clang picks up support=20 for -fpatchable-function-entry. - Naveen