From: Andrew Lunn <andrew@lunn.ch>
To: taiyun@sunnorth.com.cn
Cc: ecos-discuss@ecos.sourceware.org,
Jonathan Larmour <jifl@ecoscentric.com>
Subject: Re: [ECOS] A problem about constructor sequence
Date: Mon, 10 Sep 2007 09:35:00 -0000 [thread overview]
Message-ID: <20070910093526.GB20127@lunn.ch> (raw)
In-Reply-To: <OFAE4F14C8.27D51BC9-ON48257352.0032BD6A-48257352.0032BD79@sunnorth.com.cn>
On Mon, Sep 10, 2007 at 05:14:13PM +0800, taiyun@sunnorth.com.cn wrote:
>
> Dear all:
>
> I want to discuss something about eCos kernel, BUT I am not sure whether my
> opinion is correct or someone has reported this problem before.
> I think there is a problem with global constructor sequence. There are two
> global instances, not only they have the same initialized priority but also
> they have some relationship between each other. They are:
>
> Cyg_Thread cyg_libc_main_thread CYGBLD_ATTRIB_INIT_PRI(CYG_INIT_LIBC) = ...
> AND
> static cyg_libc_startup_dummy_constructor_class cyg_libc_startup_obj
> CYGBLD_ATTRIB_INIT_PRI(CYG_INIT_LIBC);
>
> constructor of instance cyg_libc_startup_obj will call a function named
> cyg_iso_c_start, and cyg_iso_c_start function will call
> cyg_libc_main_thread.resume(). NOTE: cyg_libc_main_thread is the fisrt
> instance I referred to.
>
> So a nature thought comes to my mind, the first instance
> cyg_libc_main_thread must be constructed before the second instance
> cyg_libc_startup_obj. Otherwise, if cyg_libc_startup_obj was constructed
> first and cyg_libc_main_thread's not initializing yet, then there must be
> some problem.
>
>
> HOWEVER, these two instances have the same priority, I think same priority
> means that any of them constructs first will not affect the final result,
> no matter who. BUT these two do matter, aren't they?
> Which first may depend on compiler, and now we are using gcc4.2 compiler
> from
> http://www.codesourcery.com/gnu_toolchains/arm/download.html
> that is arm-eabi gcc compiler, and I found that this compiler does
> construct the second instance first, and eCos kernel can't start. Instance
> of mainthread(i.e. the first instance) is not initialized and its method is
> called, this is the reason of the problem, right?
This is Jifl's domain. However i will make a stab at answering....
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)
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?
Andrew
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next prev parent reply other threads:[~2007-09-10 9:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-10 9:14 taiyun
2007-09-10 9:35 ` Andrew Lunn [this message]
2007-09-10 9:54 ` Jonathan Larmour
[not found] ` <OFD56A862C.7D2739A1-ON48257352.003F8CFF-48257352.003FE916@sunnorth.com.cn>
2007-09-10 12:58 ` [ECOS] Re: ????: " Andrew Lunn
2007-09-11 16:48 ` Andrew Lunn
2007-09-10 11:47 taiyun
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