Initial support of Embox OS about bdwgc

[ivmai]

The porting difficulties are:

• how to get main stack base (bottom)
• how to get main data root(s)

[ivmai]

How to build embox/x86 with gctest in qemu (on Ubuntu/x64):

1. prerequisites: https://github.com/embox/embox-docs/blob/master/ru/embox_quick_start_ru.md
2. git clone https://github.com/embox/embox.git
3. cd embox
4. make confload-x86
5. (cd download; wget https://mirror.iscas.ac.cn/yocto/mirror/sources/acpica-unix-20210331.tar.gz)
6. mkdir src/cmds/gctest
7. (cd src/cmds/gctest; git clone https://github.com/ivmai/bdwgc.git)
8. vi src/cmds/gctest/Mybuild // see the content below
9. vi conf/mods.conf // add line: include embox.cmd.gctest
10. make -j
11. ./scripts/qemu/auto_qemu

[ivmai]

Sample "Mybuild" file for gctest:

package embox.cmd

@AutoCmd
@Cmd(name = "gctest", help="BDWGC tests")

module gctest {
    @IncludePath("$(SRC_DIR)/cmds/gctest/bdwgc/include")
    @Cflags("-D GC_GCJ_SUPPORT")
    @Cflags("-D ENABLE_DISCLAIM")
    source "bdwgc/tests/gctest.c"
    //source "bdwgc/tests/huge.c"
    //source "bdwgc/tests/leak.c"
    //source "bdwgc/tests/middle.c"
    //source "bdwgc/tests/realloc.c"
    //source "bdwgc/tests/smash.c"
    //source "bdwgc/tests/disclaim.c"
    //source "bdwgc/tests/disclaim_bench.c"
    //source "bdwgc/tests/weakmap.c"
    @IncludePath("$(SRC_DIR)/cmds/gctest/bdwgc/include")
    @Cflags("-D GC_GCJ_SUPPORT")
    @Cflags("-D ENABLE_DISCLAIM")
    @Cflags("-D GC_ASSERTIONS")
    source "bdwgc/extra/gc.c"
}

[ivmai]

how to get main stack base (bottom)

The portable way is to use pthread_... primitives, but they are not supported in Embox yet, I've created an issue about it - embox/embox#2779

[ivmai]

Current status:

• pthread_attr_getstack() is missing
• undefined reference to _end, __data_start

[ivmai]

The portable way is to use pthread_... primitives, but they are not supported in Embox yet

Use instead, for now:

# include <kernel/thread/thread_stack.h>
...
    pthread_t self = pthread_self();
    void *stack_addr = thread_stack_get(self);
    sb -> mem_base = stack_addr + thread_stack_get_size(self);

[ivmai]

undefined reference to __data_start, _end

Use _modules_data_start and _apps_bss_end instead.

Note: this includes data/bss for all compiled-in modules and apps, size >25MB.

[ivmai]

Current limitations:

• No support of ISAs other than x86
• C++ support was not tested
• No threads support
• No memory unmaping to OS
• No malloc redirection support
• ALL_INTERIOR_POINTERS mode does not work (leads to out of memory (122MB) in gctest)
• restart of gctest command (module) leads to crash (because data & bss are not cleared between runs)