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[221.241.217.81]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21177dc3f3asm115824435ad.3.2024.11.13.15.32.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Nov 2024 15:32:44 -0800 (PST) Date: Thu, 14 Nov 2024 08:32:40 +0900 Message-ID: From: Hajime Tazaki To: geert@linux-m68k.org Cc: johannes@sipsolutions.net, linux-um@lists.infradead.org, ricarkol@google.com, Liam.Howlett@oracle.com, ebiederm@xmission.com, kees@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, gerg@linux-m68k.org, dalias@libc.org Subject: Re: [RFC PATCH v2 02/13] x86/um: nommu: elf loader for fdpic In-Reply-To: References: <8bbfe73f7f1ef9f1a4674d963d1c4e8181f33341.camel@sipsolutions.net> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/26.3 Mule/6.0 MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: BBFA5C001F X-Stat-Signature: sr8cx5i56xfp995cghx45bypcf9q8gzs X-Rspam-User: X-HE-Tag: 1731540712-836668 X-HE-Meta: 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 CVExkN3z eNJe4pa2gZuT7vdT0IE2P+7kS6MnOqMzOq1NoMykQZJ+ITGE0zq+oNl91MywrPJ3e+n28cVTrj4x8+9DzPjGtiEEbVRvSh+9F/NQljD9eCFS7lEFe8nScwi1wUUk56TKVm5vJ6J33vN7vCIwTqtlmdLf3C73WIadOK5JYHV5vnkSK0M7uz8vxzSQ5SZ872yds64VjEoCkgVo2QJN8Vt7127veQwvv7h3+xnBwetagjsLDChrENfNQ34e5aE3K8CzKiGRQ0jUwvhXWBre/8RtTG0S408GGu+vDa4PxJaPVHBjpOOUWl6fYca8iKHmL8aINbT6ysYwd5jFkIsVkD86jzlZnOmnDWFD6cIx1tUmwFpZbM+6mnGOFKS4AyAhjLlYJdBoXwLEKv0sTfs4Pw/kYdX+yRA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 13 Nov 2024 22:55:02 +0900, Geert Uytterhoeven wrote: > On Wed, Nov 13, 2024 at 2:17=E2=80=AFPM Hajime Tazaki wrote: > > On Wed, 13 Nov 2024 19:27:08 +0900, > > Geert Uytterhoeven wrote: > > > On Wed, Nov 13, 2024 at 9:37=E2=80=AFAM Johannes Berg wrote: > > > > On Wed, 2024-11-13 at 09:36 +0100, Johannes Berg wrote: > > > > > On Wed, 2024-11-13 at 09:19 +0100, Geert Uytterhoeven wrote: > > > > > > > > > > > > > > > - depends on ARM || ((M68K || RISCV || SUPERH || XT= ENSA) && !MMU) > > > > > > > > > + depends on ARM || ((M68K || RISCV || SUPERH || UM= L || XTENSA) && !MMU) > > > > > > > > > > > > > > > > s/UML/X86/? > > > > > > > > > > > > > > I guess the fdpic loader can be used to X86, but this patchse= t only > > > > > > > adds UML to be able to select it. I intended to add UML into= nommu > > > > > > > family. > > > > > > > > > > > > While currently x86-nommu is supported for UML only, this is re= ally > > > > > > x86-specific. I still hope UML will get support for other archi= tectures > > > > > > one day, at which point a dependency on UML here will become wr= ong... > > > > > > > > > > > > > > > > X86 isn't set for UML, X64_32 and X64_64 are though. > > > > > > > > > > Given that the no-MMU UM support even is 64-bit only, that probab= ly > > > > > should then really be (UML && X86_64). > > > > > > > > > > But it already has !MMU, so can't be selected otherwise, and it s= eems > > > > > that non-X86 UML > > > > > > > > ... would require far more changes in all kinds of places, so not s= ure > > > > I'd be too concerned about it here. > > > > > > OK, up to you... > > > > Indeed, this particular patch [02/13] intends to support the fdpic > > loader under the condition 1) x86_64 ELF binaries (w/ PIE), 2) on UML, > > 3) and with) !MMU configured. Given that situation, the strict check > > should be like: > > > > depends on ARM || ((M68K || RISCV || SUPERH || (UML && X86_64) || XT= ENSA) && !MMU) > > > > (as Johannes mentioned). > > > > on the other hand, the fdpic loader works (afaik) on MMU environment so, > > > > depends on ARM || (UML && X86_64) || ((M68K || RISCV || SUPERH || XT= ENSA) && !MMU) > > > > should also works, but this might be too broad for this patchset (and > > not sure if this makes a new use case). >=20 > AFAIK that depends on the architecture's MMU context structure, cfr. > the comment in commit 782f4c5c44e7d99d ("m68knommu: allow elf_fdpic > loader to be selected"), which restricts it to nommu on m68k. If it > does work on X86_64, you can drop the dependency on UML, and we're > (almost) back to my initial comment ;-) I checked and it doesn't work as-is with (UML_X86_64 && MMU). restricting nommu with UML might be a good to for this patch. even if it works, I would like to focus on UML && !MMU for this patch series since I wish to make the (initial) patchset as small as possible. If we would like to make it broadly available on x86, that would be a different patch. > > anyway, thank you for the comment. > > # I really wanted to have comments from nommu folks. >=20 > I've added some in CC... Thanks, -- Hajime