51 lines
2.3 KiB
Plaintext
51 lines
2.3 KiB
Plaintext
See README.alpha for Linux on DEC AXP info.
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This file applies mostly to Linux/Intel IA32. Ports to Linux on an M68K
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and PowerPC are also integrated. They should behave similarly, except that
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the PowerPC port lacks incremental GC support, and it is unknown to what
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extent the Linux threads code is functional.
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Incremental GC is supported on Intel IA32 and M68K.
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Dynamic libraries are supported on an ELF system. A static executable
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should be linked with the gcc option "-Wl,-defsym,_DYNAMIC=0".
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The collector appears to work with Linux threads. We have seen
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intermittent hangs in sem_wait. So far we have been unable to reproduce
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these unless the process was being debugged or traced. Thus it's
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possible that the only real issue is that the debugger loses
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signals on rare occasions.
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The garbage collector uses SIGPWR and SIGXCPU if it is used with
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Linux threads. These should not be touched by the client program.
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To use threads, you need to abide by the following requirements:
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1) You need to use LinuxThreads (which are included in libc6).
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The collector relies on some implementation details of the LinuxThreads
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package. It is unlikely that this code will work on other
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pthread implementations (in particular it will *not* work with
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MIT pthreads).
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2) You must compile the collector with -DLINUX_THREADS and -D_REENTRANT
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specified in the Makefile.
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3) Every file that makes thread calls should define LINUX_THREADS and
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_REENTRANT and then include gc.h. Gc.h redefines some of the
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pthread primitives as macros which also provide the collector with
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information it requires.
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4) Currently dlopen() is probably not safe. The collector must traverse
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the list of libraries maintained by the runtime loader. That can
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probably be an inconsistent state when a thread calling the loader is
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is stopped for GC. (It's possible that this is fixable in the
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same way it is handled for SOLARIS_THREADS, with GC_dlopen.)
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5) The combination of LINUX_THREADS, REDIRECT_MALLOC, and incremental
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collection fails in seemingly random places. This hasn't been tracked
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down yet, but is perhaps not completely astonishing. The thread package
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uses malloc, and thus can presumably get SIGSEGVs while inside the
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package. There is no real guarantee that signals are handled properly
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at that point.
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