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94 lines
3.8 KiB
Plaintext
94 lines
3.8 KiB
Plaintext
Some brief notes:
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1) This package is intended to run on FreeBSD 4.0-current or
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FreeBSD 3.X, with sources more recent than March 1, 1999, i386
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processors only.
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Compile your applications that use Linux Threads with the following
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command line options:
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-D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads -llthread
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Note that the include (-I..) directive shown here should appear before any other include
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directive that would cause the compiler to find the FreeBSD file /usr/include/pthread.h.
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Using the FreeBSD pthread.h instead of the linuxthreads pthread.h will result in an app
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fails in many odd and maybe spectacular ways.
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In order to facilitate porting applications witch expect a libpthread, you can create
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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.0 /usr/lib/libpthread.so.0
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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
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or
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-D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads -kthread
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DO NOT use libc_r with Linux Threads, and do not compile/link with
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the -pthread option (which pulls in libc_r). DO link with libc
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(which you will get by default).
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2) You should consider enabling the posix priority extensions
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in your kernel. Adding the following to your kernel config
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file before you execute config and before you remake the kernel
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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 manditory.
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3) If you plan on having lots of threads, check the sysctl value
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of kern.maxproc. Each kernel thread counts against maxproc. You
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can increase maxproc by changing the MAXUSERS value in your kernel
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config file. maxproc is set at 20 + 16 * MAXUSERS.
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4) This package should work on a normal SMP machine, however,
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there appear to be some problems introduced with the recent changes
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to the kernel signal handling, which have yet to be resolved.
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5) Be aware of the following libc issues:
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a) Not all libc calls are thread safe. Many are.
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In particular gmtime, localtime, etc are not thread
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safe. In general, where the pthreads spec calls for "_r"
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functions, these are either not provided, or if provided
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are not thread safe (in most cases) and the related
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libc calls are not thread safe. This differs somewhat
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from the FreeBSD libc_r library, where some, but not
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all, of these functions are both thread safe and have
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"_r" versions.
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b) None of the libc calls that are supposed to be
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cancellation points are implemented as such. There
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is a lot of work that needs to be done on libc before
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cancellation points will work correctly. Therefore,
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while linux threads has the cancel functions implemented,
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deferred cancellation will not really do anything, since
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the co-operation needed from libc is not there.
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6) There is a call implemented for FreeBSD (see stack.c):
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int _pthread_setstackspacing(size_t spacing, size_t guardsize)
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By default, Linux Threads spaces thread stacks 2MB apart, and
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makes each thread stack an "autogrow" stack. If you know that
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your maximum stack for any thread can be less than that, you
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can decrease the spacing by calling this function. It must
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be called before any other pthreads function calls, and it
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will only succeed the first time its called. Note that the
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pthread TLS and the guardsize will be included in the spacing.
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ie. maximum stack size = spacing - TLSpagesize - guardsize.
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The spacing must be a power of 2 times the pagesize (and if its
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not, it will be rounded up to the next highest value that is).
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7) Note that this is an older version of linuxthreads. More current
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versions are at http://www.kernel.org/pub/linux/libs/glibc.
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