| The collector has at various times been compiled under Windows 95 & NT, |
| with the original Microsoft SDK, with Visual C++ 2.0, 4.0, and 6, with |
| the GNU win32 environment, with Borland 4.5, with Watcom C, and recently |
| with the Digital Mars compiler. It is likely that some of these have been |
| broken in the meantime. Patches are appreciated. |
| |
| It runs under both win32s and win32, but with different semantics. |
| Under win32, all writable pages outside of the heaps and stack are |
| scanned for roots. Thus the collector sees pointers in DLL data |
| segments. Under win32s, only the main data segment is scanned. |
| (The main data segment should always be scanned. Under some |
| versions of win32s, other regions may also be scanned.) |
| Thus all accessible objects should be accessible from local variables |
| or variables in the main data segment. Alternatively, other data |
| segments (e.g. in DLLs) may be registered with the collector by |
| calling GC_init() and then GC_register_root_section(a), where |
| a is the address of some variable inside the data segment. (Duplicate |
| registrations are ignored, but not terribly quickly.) |
| |
| (There are two reasons for this. We didn't want to see many 16:16 |
| pointers. And the VirtualQuery call has different semantics under |
| the two systems, and under different versions of win32s.) |
| |
| Win32 applications compiled with some flavor of gcc currently behave |
| like win32s applications, in that dynamic library data segments are |
| not scanned. (Gcc does not directly support Microsoft's "structured |
| exception handling". It turns out that use of this feature is |
| unavoidable if you scan arbitrary memory segments obtained from |
| VirtualQuery.) |
| |
| The collector test program "gctest" is linked as a GUI application, |
| but does not open any windows. Its output appears in the file |
| "gc.log". It may be started from the file manager. The hour glass |
| cursor may appear as long as it's running. If it is started from the |
| command line, it will usually run in the background. Wait a few |
| minutes (a few seconds on a modern machine) before you check the output. |
| You should see either a failure indication or a "Collector appears to |
| work" message. |
| |
| The cord test program has not been ported (but should port |
| easily). A toy editor (cord/de.exe) based on cords (heavyweight |
| strings represented as trees) has been ported and is included. |
| It runs fine under either win32 or win32S. It serves as an example |
| of a true Windows application, except that it was written by a |
| nonexpert Windows programmer. (There are some peculiarities |
| in the way files are displayed. The <cr> is displayed explicitly |
| for standard DOS text files. As in the UNIX version, control |
| characters are displayed explicitly, but in this case as red text. |
| This may be suboptimal for some tastes and/or sets of default |
| window colors.) |
| |
| In general -DREDIRECT_MALLOC is unlikely to work unless the |
| application is completely statically linked. |
| |
| The collector normally allocates memory from the OS with VirtualAlloc. |
| This appears to cause problems under Windows NT and Windows 2000 (but |
| not Windows 95/98) if the memory is later passed to CreateDIBitmap. |
| To work around this problem, build the collector with -DUSE_GLOBAL_ALLOC. |
| This is currently incompatible with -DUSE_MUNMAP. (Thanks to Jonathan |
| Clark for tracking this down. There's some chance this may be fixed |
| in 6.1alpha4, since we now separate heap sections with an unused page.) |
| |
| For Microsoft development tools, rename NT_MAKEFILE as |
| MAKEFILE. (Make sure that the CPU environment variable is defined |
| to be i386.) In order to use the gc_cpp.h C++ interface, all |
| client code should include gc_cpp.h. |
| |
| If you would prefer a VC++.NET project file, ask boehm@acm.org. One has |
| been contributed, but it seems to contain some absolute paths etc., so |
| it can presumably only be a starting point, and is not in the standard |
| distribution. It is unclear (to me, Hans Boehm) whether it is feasible to |
| change that. |
| |
| Clients may need to define GC_NOT_DLL before including gc.h, if the |
| collector was built as a static library (as it normally is in the |
| absence of thread support). |
| |
| For GNU-win32, use the regular makefile, possibly after uncommenting |
| the line "include Makefile.DLLs". The latter should be necessary only |
| if you want to package the collector as a DLL. The GNU-win32 port is |
| believed to work only for b18, not b19, probably due to linker changes |
| in b19. This is probably fixable with a different definition of |
| DATASTART and DATAEND in gcconfig.h. |
| |
| For Borland tools, use BCC_MAKEFILE. Note that |
| Borland's compiler defaults to 1 byte alignment in structures (-a1), |
| whereas Visual C++ appears to default to 8 byte alignment (/Zp8). |
| The garbage collector in its default configuration EXPECTS AT |
| LEAST 4 BYTE ALIGNMENT. Thus the BORLAND DEFAULT MUST |
| BE OVERRIDDEN. (In my opinion, it should usually be anyway. |
| I expect that -a1 introduces major performance penalties on a |
| 486 or Pentium.) Note that this changes structure layouts. (As a last |
| resort, gcconfig.h can be changed to allow 1 byte alignment. But |
| this has significant negative performance implications.) |
| The Makefile is set up to assume Borland 4.5. If you have another |
| version, change the line near the top. By default, it does not |
| require the assembler. If you do have the assembler, I recommend |
| removing the -DUSE_GENERIC. |
| |
| There is some support for incremental collection. This is |
| currently pretty simple-minded. Pages are protected. Protection |
| faults are caught by a handler installed at the bottom of the handler |
| stack. This is both slow and interacts poorly with a debugger. |
| Whenever possible, I recommend adding a call to |
| GC_enable_incremental at the last possible moment, after most |
| debugging is complete. Unlike the UNIX versions, no system |
| calls are wrapped by the collector itself. It may be necessary |
| to wrap ReadFile calls that use a buffer in the heap, so that the |
| call does not encounter a protection fault while it's running. |
| (As usual, none of this is an issue unless GC_enable_incremental |
| is called.) |
| |
| Note that incremental collection is disabled with -DSMALL_CONFIG. |
| |
| James Clark has contributed the necessary code to support win32 threads. |
| Use NT_THREADS_MAKEFILE (a.k.a gc.mak) instead of NT_MAKEFILE |
| to build this version. Note that this requires some files whose names |
| are more than 8 + 3 characters long. Thus you should unpack the tar file |
| so that long file names are preserved. To build the garbage collector |
| test with VC++ from the command line, use |
| |
| nmake /F ".\gc.mak" CFG="gctest - Win32 Release" |
| |
| This requires that the subdirectory gctest\Release exist. |
| The test program and DLL will reside in the Release directory. |
| |
| This version relies on the collector residing in a dll. |
| |
| This version currently supports incremental collection only if it is |
| enabled before any additional threads are created. |
| Version 4.13 attempts to fix some of the earlier problems, but there |
| may be other issues. If you need solid support for win32 threads, you |
| might check with Geodesic Systems. Their collector must be licensed, |
| but they have invested far more time in win32-specific issues. |
| |
| Hans |
| |
| Ivan V. Demakov's README for the Watcom port: |
| |
| The collector has been compiled with Watcom C 10.6 and 11.0. |
| It runs under win32, win32s, and even under msdos with dos4gw |
| dos-extender. It should also run under OS/2, though this isn't |
| tested. Under win32 the collector can be built either as dll |
| or as static library. |
| |
| Note that all compilations were done under Windows 95 or NT. |
| For unknown reason compiling under Windows 3.11 for NT (one |
| attempt has been made) leads to broken executables. |
| |
| Incremental collection is not supported. |
| |
| cord is not ported. |
| |
| Before compiling you may need to edit WCC_MAKEFILE to set target |
| platform, library type (dynamic or static), calling conventions, and |
| optimization options. |
| |
| To compile the collector and testing programs use the command: |
| wmake -f WCC_MAKEFILE |
| |
| All programs using gc should be compiled with 4-byte alignment. |
| For further explanations on this see comments about Borland. |
| |
| If the gc is compiled as dll, the macro ``GC_DLL'' should be defined before |
| including "gc.h" (for example, with -DGC_DLL compiler option). It's |
| important, otherwise resulting programs will not run. |
| |
| Ivan Demakov (email: ivan@tgrad.nsk.su) |
| |
| |