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62 lines
2.2 KiB
Plaintext
62 lines
2.2 KiB
Plaintext
This file documents Google's modified version of glibc, known as GRTE
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(Google Run Time Environment). GRTE serves as the common C library for
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internal Google applications running on production systems.
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While GRTE is nearly identical to stock glibc, it does have a number
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of local changes. These run the gamut from patches that were
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submitted but not accepted for trunk glibc, to workarounds for quirks
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of Google infrastructure, to extensions that are critical for the
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proper functioning of applications. The ideal, however, is to have no
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local changes at all.
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GRTE versions are identified by a small integer, which generally
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corresponds to a particular glibc version. GRTE v4 is based on
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glibc-2.19, while GRTE v5 is based on glibc-2.27, for instance.
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BUILDING GRTE WITH GCC
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When using GCC, GRTE v4 and later will build with native
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configure/make in the usual way for glibc. For v4, nscd does not
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work, so add --disable-nscd when configuring.
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Supported architectures include x86_64 and ppc64le.
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Testsuites will likely have some additional failures.
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BUILDING GRTE WITH CLANG
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GRTE v5 and later can also be built with clang and (optionally) lld.
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LLVM support for GNU source code continues to evolve (as of June
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2018), so the process is less straightforward, and likely to change
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from what is documented here. There are a number of glibc patches
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that make this work, including additional configure options mentioned
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below.
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The minimum version of clang is 6.0.0. If lld is to be used for linking,
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it needs to be newer than 6.0.0.
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Configure:
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CC=path-to-llvm/clang CXX=path-to-llvm/clang \
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../glibc/configure --disable-werror --with-clang --disable-float128 \
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--with-lld --with-default-link --prefix=/something
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To build with BFD ld as linker, omit the "--with-lld
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--with-default-link". (Gold has had problems in the past.)
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Build:
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make
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make install
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To test:
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make check
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Testsuite results will show many unexpected failures beyond the
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GCC-compiled results; about 390 for x86-64. These are a combination
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of known bugs in clang, and issues with conformance to old standards
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predating clang. Note that the clang build still needs symlinks to
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libgcc and libstdc++ in the installed library directory, so that
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thread cancellation tests pass.
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