Hi, I was also wondering about this Y2038 thingy and did some experiments. I'm reporting what I found to document it, but don't see much actionable stuff here. Many thanks to Arnd Bergmann for his input.
Attempt #1: rebootstrap Given that I develop rebootstrap, attempting to use it for a time64 bootstrap seemed quite natural. I've been talking to this with Steve multiple times including DC22. The question was how to plug it in. In the end I went for Arnd's suggestion to set DPKG_*_APPEND variables to modify dpkg-buildflags. Not every package uses these flags, but a majority do. For a survey, this is probably good enough. Things went somewhat far. The first issue was zlib. There isn't much to say about it: https://github.com/madler/zlib/issues/447 Then the libprelude build failed with symbol issues. It happens to build a C++ library and its symbols are dependent on time types. Unsurprising. This is a case where we do break ABI. Then it occured to me that not failing does not imply not being affected right? You can break ABI without failing the build. So as a detection method this has a significant risk of false negatives. For just bootstrapping an incompatible time64 armhf, this method should mostly just work. Would someone like to have the resulting .debs? What would do with them? Attempt #2: reproducible My other favourite QA tool is reproducible builds. So how about building and comparing binary packages? Unfortunately, build flags participate in build ids. That directly implies a high risk of false positives and/or manual work. Without further ado, here we go. .debs unchanged: * base-files * db-defaults * coreutils * diffutils * findutils * libonig * libidn * libidn2 * libpipeline * libpthread-stubs * libsm * gzip Question: How many of these ignore dpkg-buildflags? minor changes: * gmp: build-id and #define __GMP_CFLAGS * guile-3.0: build-id and recorded build path unclear: * fribidi: only libfribidi-bin changes, probably harmless ftbfs: * zlib: see earlier starts using symbols such as __stat64_time64, __ioctl_time64: * acl * attr * base-passwd * bash * blt * bsdmainutils * bzip2 * c-ares * curl * dash * debianutils * dpkg * e2fsprogs * expat * file * flex * fontconfig * freetype * fuse * glib2.0 * gnupg2 * gpm * groff * hostname * icu * jansson * jemalloc * keyutils * kmod * krb5 * libassuan * libatomic-ops * libbsd * libcap2 * libdebian-installer * libev * libevent * libgc * libgcrypt20 * libice * libksba * libmd * libnsl * libpng1.6 * libsepol starts using large file symbols, but no time64 symbols: * libffi starts using symbols such as above, but also changes C++ symbols: * apt unreproducible for other non-time reasons: * binutils After this sample, it became clear that this method is also not very helpful. While it shows that basically everything is affected, it doesn't give a good handle on ABI breakage either. Please Cc me in replies as I am not subscribed. Helmut
