[ECOS] Re: ????: Re: [ECOS] A problem about constructor sequence

[Andrew Lunn <andrew@lunn.ch>]

On Mon, Sep 10, 2007 at 07:38:04PM +0800, eCos@sunnorth.com.cn wrote:
> >I don't see how this can break anything. The scheduler is disabled at
> >this point anyway. The the resume call just marks the thread as
> >runable, but it won't get run until a lot later.
> >Jifl: Is this O.K?
> 
> Thanks a lot, really appreciate your answers.
> 
> But I still doubt, I have checked the source code of thread.cxx, I found 
> that thread's state is set to SUSPENDED in Cyg_Thread class's constructor 
> and suspend_count variable is set to 1(1 represents suspended and 0 
> represents ready or running, right?), so when Cyg_Thread's resume method 
> is called, suspend_count will be set to 0 to indicate this thread is not 
> suspended, and state of thread will be set, too. 
> 
> cyg_libc_main_thread is an instance of Cyg_Thread, so it must follow this 
> procedure. If it was constructed first, then when instance 
> cyg_libc_startup_obj is constructed, cyg_libc_main_thread.resume will be 
> called.
> BUT if cyg_libc_main_thread is constructed after cyg_libc_startup_obj, I 
> think this case will cause problem. Because cyg_libc_startup_obj will call 
> cyg_libc_main_thread.resume, NOW I know scheduler is not start yet till 
> this point, so it just sets some flag, it is ok.
> BUT after cyg_libc_startup_obj is constructed, then will be 
> cyg_libc_main_thread. In constructor of cyg_libc_main_thread, thread's 
> state will be set to SUSPENDED, and will never be resumed, isn't it?

What i said was:

> I think you are correct. Probably the second should be
>
> static cyg_libc_startup_dummy_constructor_class cyg_libc_startup_obj
>                                    CYGBLD_ATTRIB_INIT_AFTER(CYG_INIT_LIBC)

The _AFTER() change means that cyg_libc_startup_obj is constructed
after all other constructors of priority CYG_INIT_LIBC are
called. Thus cyg_libc_main_thread will always be called first.

Or am i missing something here?

   Andrew

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