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b=Mh20iy/fPgoKsPFqkHOMkSvPPs3YobSnTzSECvBMzNm1M8s6vO83AlQC6ilY4EOTy 8sOXH1quEckXBhwBGWJj3cHU+7AJwHqGK3p8fjuVfk/jjnSzsPPyPutWZjpiLaoAyt gCdMIRxqqGOm0zxE4aSYMab0Wodh06NeE+MsysKpcDwBDbIlcnfS/wkLiVdVzhzICG 4UjcQOTTx+aFwRJE1QaD8Cvt4dl3qLXOUDKmxsy7E1fx9TesQtzL9Q+NmezjMQehNS 0WMvz7jO6i8duGQNOX4hQOm+ZTVOc7wkWM1vHVgf8whVZyCCBz2ju8SWZpi8Hlqbp4 o2gZF74Dfgnvw== Date: Tue, 4 Jun 2024 09:51:55 +0100 From: Conor Dooley To: Alexandre Ghiti Cc: yunhui cui , Catalin Marinas , Will Deacon , Thomas Bogendoerfer , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Paul Walmsley , Palmer Dabbelt , Albert Ou , Andrew Morton , Ved Shanbhogue , Matt Evans , Dylan Jhong , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-mm@kvack.org Subject: Re: [External] [PATCH RFC/RFT v2 3/4] riscv: Stop emitting preventive sfence.vma for new vmalloc mappings Message-ID: <20240604-dazzling-envy-1dcf111eb2c5@spud> References: <20240131155929.169961-1-alexghiti@rivosinc.com> <20240131155929.169961-4-alexghiti@rivosinc.com> MIME-Version: 1.0 Content-Type: multipart/signed; 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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jun 04, 2024 at 09:17:26AM +0200, Alexandre Ghiti wrote: > On Tue, Jun 4, 2024 at 9:15=E2=80=AFAM Alexandre Ghiti wrote: > > On Tue, Jun 4, 2024 at 8:21=E2=80=AFAM yunhui cui wrote: > > > > > > As for the current status of the patch, there are two points that can > > > be optimized: > > > 1. Some chip hardware implementations may not cache TLB invalid > > > entries, so it doesn't matter whether svvptc is available or not. Can > > > we consider adding a CONFIG_RISCV_SVVPTC to control it? >=20 > That would produce a non-portable kernel. But I'm not opposed to that > at all, let me check how we handle other extensions. Maybe @Conor > Dooley has some feedback here? To be honest, not really sure what to give feedback on. Could you elaborate on exactly what the option is going to do? Given the portability concern, I guess you were proposing that the option would remove the preventative fences, rather than your current patch that removes them via an alternative? I don't think we have any extension related options that work like that at the moment, and making that an option will just mean that distros that look to cater for multiple platforms won't be able to turn it on. Thanks, Conor. --v+mLtQDAp6jKleQy Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZl7VpwAKCRB4tDGHoIJi 0htmAP9lKpWaps7KNiXD+LLzGjaogNRPLVfDE+cLSH8OGRjL0gD/b1+iNEj7/u9+ OImeR7875AIcwdnxddUdj3oiiMB/6AA= =s00j -----END PGP SIGNATURE----- --v+mLtQDAp6jKleQy--