Change the last linux 64-bit snapshot #17288
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I'm rotating in some CentOS 5.10 bots so we *actually* build on Linux 2.6.18 like we advertise doing so. Currently the snapshots are incompatible with CentOS 5.10 due to snapshots requiring glibc 2.6 and CentOS 5.10 having glibc 2.5. It turns out that rustc only requires *one* symbol from glibc 2.6, which is `futimens`. The rust distribution itself does not use this symbol, but LLVM conditionally detects it and then uses it. This symbol isn't even called as part of the compilation process, so we don't even need it! The new snapshot was generated following these instructions [1]: 1. Download the current x86_64 linux snapshot and unpack it. 2. Open the rustc binary in a hex editor. 3. Change the linkage against glibc 2.6 from strong to *weak* 4. Write changes and re-run src/etc/make-snapshot.py 5. Upload new tarball to S3 On CentOS 5.10 a warning is printed each time the snapshot runs that the symbol cannot be found (anyone with glibc 2.6+ does not have this warning printed). The key part is that we can *bootstrap* on CentOS 5.10 at this point. The next snapshot will be naturally compatible with glibc 2.3 (even older!) and will not need to be manually edited. [1]: http://jamesbond3142.no-ip.org/wiki/wiki.cgi/NewAppsOnOldGlibc
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I'm rotating in some CentOS 5.10 bots so we *actually* build on Linux 2.6.18 like we advertise doing so. Currently the snapshots are incompatible with CentOS 5.10 due to snapshots requiring glibc 2.6 and CentOS 5.10 having glibc 2.5. It turns out that rustc only requires *one* symbol from glibc 2.6, which is `futimens`. The rust distribution itself does not use this symbol, but LLVM conditionally detects it and then uses it. This symbol isn't even called as part of the compilation process, so we don't even need it! The new snapshot was generated following these instructions [1]: 1. Download the current x86_64 linux snapshot and unpack it. 2. Open the rustc binary in a hex editor. 3. Change the linkage against glibc 2.6 from strong to *weak* 4. Write changes and re-run src/etc/make-snapshot.py 5. Upload new tarball to S3 On CentOS 5.10 a warning is printed each time the snapshot runs that the symbol cannot be found (anyone with glibc 2.6+ does not have this warning printed). The key part is that we can *bootstrap* on CentOS 5.10 at this point. The next snapshot will be naturally compatible with glibc 2.3 (even older!) and will not need to be manually edited. [1]: http://jamesbond3142.no-ip.org/wiki/wiki.cgi/NewAppsOnOldGlibc
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Will we need to do something similar for linux-i386? |
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Thankfully no, the snapshot builders always use the 64-bit triple as the build triple. Snapshots are only downloaded for the build triple, so we should be good. |
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I'm rotating in some CentOS 5.10 bots so we actually build on Linux 2.6.18
like we advertise doing so. Currently the snapshots are incompatible with CentOS
5.10 due to snapshots requiring glibc 2.6 and CentOS 5.10 having glibc 2.5.
It turns out that rustc only requires one symbol from glibc 2.6, which is
futimens. The rust distribution itself does not use this symbol, but LLVMconditionally detects it and then uses it. This symbol isn't even called as part
of the compilation process, so we don't even need it!
The new snapshot was generated following these instructions 1:
On CentOS 5.10 a warning is printed each time the snapshot runs that the symbol
cannot be found (anyone with glibc 2.6+ does not have this warning printed). The
key part is that we can bootstrap on CentOS 5.10 at this point. The next
snapshot will be naturally compatible with glibc 2.3 (even older!) and will not
need to be manually edited.