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80 lines
3.5 KiB
Plaintext
80 lines
3.5 KiB
Plaintext
Some brief notes:
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1) This package is intended to run on FreeBSD 5.0-current or
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FreeBSD 4.X i386 processors only.
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Compile your applications that use LinuxThreads with the following
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command line options:
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-D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads -llthread -llgcc_r
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Note that the include (-I<path>) directive shown here should appear before any
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other include directive that would cause the compiler to find the FreeBSD file
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/usr/include/pthread.h. Using the FreeBSD pthread.h instead of the linuxthreads
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pthread.h will result in an app fails fails in many odd and maybe spectacular
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ways.
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In order to facilitate porting applications which expect a libpthread, you can
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create the following symlinks if you want:
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ln -s /usr/local/lib/liblthread.a /usr/lib/libpthread.a
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ln -s /usr/local/lib/liblthread_p.a /usr/lib/libpthread_p.a
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ln -s /usr/local/lib/liblthread.so.2 /usr/lib/libpthread.so.2
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ln -s /usr/local/lib/liblthread.so.0 /usr/lib/libpthread.so
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/sbin/ldconfig -m /usr/lib
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If you do this, you can instead use:
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-D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads -lpthread -llgcc_r
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or
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-D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads -kthread -llgcc_r
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Do not use libc_r with LinuxThreads, and do not compile/link with the -pthread
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option (which pulls in libc_r). Rather, link with libc (which you will get by
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default).
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2) You should consider enabling the posix priority extensions in your kernel.
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Adding the following to your kernel config file before you execute config and
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before you re-make the kernel should suffice.
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options "P1003_1B"
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options "_KPOSIX_PRIORITY_SCHEDULING"
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options "_KPOSIX_VERSION=199309L"
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These options are not mandatory.
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3) If you plan on having lots of threads, check the sysctl value of
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kern.maxproc. Each kernel thread counts against maxproc. You can increase
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maxproc by changing the MAXUSERS value in your kernel config file. maxproc is
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set at 20 + 16 * MAXUSERS.
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4) Be aware of the following libc issues:
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a) Not all libc calls are thread safe. In particular gmtime, localtime, etc
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are not thread safe. In general, where the pthreads spec calls for "_r"
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functions, these are either not provided, or if provided are not thread safe
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(in most cases) and the related libc calls are not thread safe. This differs
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somewhat from the FreeBSD libc_r library, where some, but not all, of these
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functions are both thread safe and have "_r" versions.
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b) Not all of the libc calls that are supposed to be cancellation points are
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implemented as such. While linux threads has the cancel functions
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implemented, deferred cancellation will not work as required by POSIX
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1003.1c-1995, since the co-operation needed from libc is not complete.
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5) Known problems and issues:
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It is possible that the instructions given above for including liblgcc_r
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are not sufficent. liblgcc_r is a version of libgcc_r linked against this
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linuxthreads package. It is intended that applications link against this,
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rather than libgcc_r (which is linked against libc_r) or libgcc (which is not
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thread safe).
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The normal gcc link options cause libgcc to be included twice in the link line
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(and libgcc_r twice when linking with the -pthread option). It is therefore
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possible that a custom link line needs to be generated that specifically
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excludes the default libgcc and which includes liblgcc_r twice. There are no
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known problems resulting from the link procedure suggested above. However,
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compiling/linking with the "-v" option will illustrate the issue, where libgcc
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is included twice in addition to liblgcc_r.
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