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([2804:1b3:a7c1:7e99:6983:51e0:457e:734]) by smtp.gmail.com with ESMTPSA id m17-20020a0568080f1100b0035028730c90sm1824744oiw.1.2023.01.27.09.40.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Jan 2023 09:40:16 -0800 (PST) Message-ID: Date: Fri, 27 Jan 2023 14:40:14 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.7.0 Subject: Re: time64 / Large File Support: 2) default time64 breaks legacy 32bit binaries Content-Language: en-US To: Paul Eggert Cc: libc-alpha@sourceware.org References: <10857996.18pcnM708K@pinacolada> <7196595.N7aMVyhfb1@pinacolada> <7271eb94-b5d7-69d6-9be0-ca1afda29a50@cs.ucla.edu> <2342ab66-6ac6-17d8-3693-8e2fd93fc8a1@linaro.org> From: Adhemerval Zanella Netto Organization: Linaro In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-6.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 26/01/23 23:38, Paul Eggert wrote: > On 1/26/23 05:21, Adhemerval Zanella Netto via Libc-alpha wrote: >> So although I am not quite against --enable-hard-sys-types64, I personally >> think we should do something more drastically (which not all other glibc >> developers agree) and flip the switch to enable 64-bit time_t *as default* >> and document 32-bit is opt-in. > > Just to clarify, there are two issues here: > > A. Should _FILE_OFFSET_BITS and _TIME_BITS default to 64 instead of to 32? That is my understanding to make 64-bit time_t the default ABI. > > B. Should _FILE_OFFSET_BITS=64 and _TIME_BITS=64 be the *only* values supported? That is, should the old API (with 32-bit time_t, off_t, etc.) be available only to old 32-bit executables, and not to newly-built 32-bit executables? That's a good question and I think it does make sense to move the non-LFS and 32-bit time_t API to compat code and only provide 64-bif off_t/time_t support. > > As I understood it, the proposal was that (A) and (B) both default to "no", but '.../configure --enable-hard-sys-types64' would change both (A) and (B) to "yes". > > It sounds like you're proposing a more drastic approach, in which (A) and (B) both default to "yes", but '.../configure --disable-hard-sys-types64' changes them both to "no". Is that right? Not really, my proposal was initial to set (A) to 'yes' but still allow new programs to be built with -D_FILE_OFFSET_BITS=32 and -D_TIME_BITS=32. But making the later compat symbols seems also a good thing to cement for good the old interfaces. I am really trying to avoid a configure switch (such as --disable-hard-sys-types64), they tend to be become rotten and fail due lack of testing (and also add some fragmentation due each distro using different switch). > > Another possibility is to adopt the milder approach for glibc version N, and switch to the more drastic approach in glibc version N+1.This would give distros time to test this new configure-time option before it's the default. Do you mean add the --enable-hard-sys-types64 on glibc N, and then remove it on N+1 and make the 64-bit the default?