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On 02/13/2011 04:04 PM, Perry Smith wrote: |
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> On Feb 11, 2011, at 3:23 AM, Michael Haubenwallner wrote: |
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>> |
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>> How I prefer doing "shared libraries" with "soname" on AIX now is: |
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>> |
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>> *) Create the shared object "shr.o" (using '-G' linker flag). |
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>> *) Set the LOADONLY flag for "shr.o" (using 'strip -e'). |
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>> *) Create the Import File "shr.imp", containing |
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>> - this header line, being the "soname" emulation: |
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>> #! libNAME.so.1(shr.o) |
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>> - another header line telling the bits used: |
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>> # 32 |
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>> or |
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>> # 64 |
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>> - the list of symbols exported. |
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>> *) Create the archive library "libNAME.so.1.2.3" from both |
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>> "shr.imp" and "shr.o". |
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>> *) Create the symlinks as usual: |
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>> libNAME.so.1 -> libNAME.so.1.2.3 |
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>> libNAME.so -> libNAME.so.1.2.3 |
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>> *) Create the static library archive "libNAME.a" from static objects. |
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> |
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> Do you recall the advantage of having a import file plus the shared |
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> object in the archive? What problem does that solve that having |
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> just the shared object creates? |
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Actually I've used to do standalone both Import File libNAME.so and |
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shared object libNAME.so.1 - which indeed did work for Prefix so far. |
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However, to get a better chance for upstream integration - especially |
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into libtool, I've had to look at the Big Picture: |
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*) Multilib: |
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Using an archive, it is possible to provide both 32/64 bit shared |
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objects within one single file - much like AIX libc.a and others do. |
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We don't do multilib in Prefix. |
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*) Dynamically load both with and without version number: |
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dlopen("libNAME.so(shr.o)", RTLD_MEMBER), besides the preferred |
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dlopen("libNAME.so.1(shr.o)", RTLD_MEMBER), and even |
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dlopen("libNAME.so.1.2.3(shr.o)", RTLD_MEMBER) does work. |
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Must admit that I've not seen a package I've built on AIX so far |
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where this actually is necessary. |
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*) All-in-one file to call "shared library (with soname)": |
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This is necessary to allow wrapping the linker to support the '-soname' linker |
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flag, so existing packages without explicit AIX build support can work right |
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out of the box. This even includes those symlinks known from ELF-world. |
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For Prefix this does help a lot as sys-devel/native-cctools provides this |
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ld-wrapper now: I've been able to drop *all* AIX-specific patches and |
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handling from within app-arch/bzip2-1.0.6-r1 now. |
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These (and more) reasons are also listed in libtool-list archives: |
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http://lists.gnu.org/archive/html/libtool/2011-01/msg00023.html |
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http://lists.gnu.org/archive/html/libtool/2011-02/msg00000.html |
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/haubi/ |
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-- |
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Michael Haubenwallner |
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Gentoo on a different level |
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