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[221.241.217.81]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2f2a2449c45sm265640a91.46.2024.12.13.14.21.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Dec 2024 14:21:39 -0800 (PST) Date: Sat, 14 Dec 2024 07:21:35 +0900 Message-ID: From: Hajime Tazaki To: ebiederm@xmission.com Cc: linux-um@lists.infradead.org, ricarkol@google.com, Liam.Howlett@oracle.com, kees@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v5 02/13] x86/um: nommu: elf loader for fdpic In-Reply-To: <87r06bz1uf.fsf@email.froward.int.ebiederm.org> References: <87r06d0ymg.fsf@email.froward.int.ebiederm.org> <87bjxf1he1.fsf@email.froward.int.ebiederm.org> <87r06bz1uf.fsf@email.froward.int.ebiederm.org> 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=US-ASCII X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241213_142141_595621_1CE1A88D X-CRM114-Status: GOOD ( 25.60 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org On Sat, 14 Dec 2024 06:53:44 +0900, Eric W. Biederman wrote: > > config BINFMT_ELF > > bool "Kernel support for ELF binaries" > > - depends on MMU > > select ELFCORE > > default y > > help > > @@ -58,7 +57,7 @@ config ARCH_USE_GNU_PROPERTY > > config BINFMT_ELF_FDPIC > > bool "Kernel support for FDPIC ELF binaries" > > default y if !BINFMT_ELF > > - depends on ARM || ((M68K || RISCV || SUPERH || UML || XTENSA) && !MMU) > > + depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU) > > select ELFCORE > > help > > ELF FDPIC binaries are based on ELF, but allow the individual load > > You have my apologies I was most definitely confused. BINFMT_ELF > currently does not work without an MMU. no problem. > >> I just react a little strongly to the assertion that elf_fdpic is > >> the only path when I don't see why that should be. > >> > >> Especially for an architecture like user-mode-linux where I would expect > >> it to run the existing binaries for a port. > > > > I understand your concern, and will try to work on improving this > > situation a bit. > > > > Another naive question: are there any past attempts to do the similar > > thing (binfmt_elf without MMU) ? > > At this point what I would recommend is: > > Merge your original patch. Get nommu UML working with binfmt_elf_fdpic.c. > I think it is a proper superset of ELF functionality. > > Then I would make it a long term goal to see about removing redundancy > between binfmt_elf.c and binfmt_elf_fdpic.c with a view to merging them > in the long term. > > There is a lot of mostly duplicate code between the two and > binfmt_elf_fdpic.c does not get half the attention and use binfmt_elf.c > gets. thanks for the recommendation. I'll go for this direction. It would be great if nommu arch (at least) UML can use the regular binfmt_elf. -- Hajime