Documentation reentrancy

[Carl Denzen Van]

Hello Jeff,

I cannot figure out how to "Set the __DYNAMIC_REENT__ flag for the  
platform" (and I think you named it also "__DYNAMIC_REENTRANCY__").  
Where can I find documentation?
Do I have to call the _getreent() myself in the stubs? Or is it  
already implemented at another level in newlib?
In the working libgloss/mn10300 I did not find anything about  
reentrancy in the way you explained.

Carl.



Op 16-feb-2006, om 0:21 heeft Jeff Johnston het volgende geschreven:

> Carl Denzen Van wrote:
>> Thank you. I will implement choice 4.
>
>
>> And meanwhile I ran into the next errors when I compile the  
>> simple  stubs from the docs:
>
> I wouldn't suggest implementing those strictly from the docs as  
> they have the wrong names to start with and there is already an  
> implemented library of these stubs available for you in libgloss/ 
> libnosys (sans _exit and crt0 which you should provide in  
> assembler).  You simply add -lnosys to the end of your link or  
> embed the reference in your ld script  or spec file.
>
> I usually suggest looking at working implementations (e.g. libgloss/ 
> mn10300).
>
> -- Jeff J.
>
>
>
>> stubsc.c: In function `sbrk':
>> stubsc.c:108: `stack_ptr' undeclared (first use in this function)
>> stubsc.c:108: (Each undeclared identifier is reported only once
>> stubsc.c:108: for each function it appears in.)
>> stubsc.c:110: warning: implicit declaration of function `_write'
>> stubsc.c: At top level:
>> stubsc.c:122: conflicting types for `stat'
>> /usr/local/m6811-elf/include/sys/stat.h:124: previous declaration  
>> of  `stat'
>> stubsc.c:131: warning: `struct tms' declared inside parameter list
>> stubsc.c:131: warning: its scope is only this definition or   
>> declaration, which is probably not what you want.
>> stubsc.c: In function `write':
>> stubsc.c:162: warning: implicit declaration of function `writechar'
>> Another improvement to the documentation would be to mention the   
>> files to be included. I include (after "grep"ping an evening for  
>> the  missing entries):
>> #include <sys/types.h>
>> #include <sys/stat.h>
>> #include <stdlib.h>
>> #include <errno.h>
>> #undef errno
>> extern int errno;
>> Carl van Denzen. (trying to make it running on Motorola 6811)
>> Op 15-feb-2006, om 23:29 heeft Jeff Johnston het volgende geschreven:
>>> Carl van Denzen wrote:
>>>
>>>> I am working on a very simple application, but do not know what  
>>>> is  the best solution. The documentation is not clear enough  
>>>> (for me).
>>>>  From the mailing list, the preferred way is NOT to use the   
>>>> _xxxx_r functions. Mention this preference in the docs.
>>>> The documentation phrase "Each function which uses the global   
>>>> reentrancy structure uses the global variable _impure_ptr,  
>>>> which  points to a reentrancy structure." is confusing. Is there  
>>>> really a  GLOBAL reentrancy structure?
>>>
>>>
>>> Yes.  I guess it would be clearer to call it the default  
>>> reentrancy  structure that is of global-scope.  It is used by  
>>> functions that have
>>> both a regular and _r form.  The regular form of the function  
>>> calls  the _r version, passing the default reentrancy structure  
>>> "or" if  __DYNAMIC_REENTRANCY__ is set to true, it calls the  
>>> function  __getreent() to get a reentrancy structure which is  
>>> then passed to  the _r version.
>>>
>>> This leads to the following choices:
>>>
>>> 1. With no threading, just let functions use the default reentrancy
>>>    struct (i.e. do nothing and don't worry about calling _r  
>>> routines).
>>> 2. Call _r routines only and manually pass an appropriate reentrancy
>>>    struct (one allocated per thread).
>>> 3. Update the _impure_ptr manually at thread switches and call the
>>>    regular forms of functions (i.e. don't worry about calling _r
>>>    suffixed functions).
>>> 4. Set the __DYNAMIC_REENT__ flag for the platform and
>>>    provide a __getreent() function that returns a unique reentrancy
>>>    struct for the current running thread.  Call regular forms
>>>    of functions.
>>>
>>>> An improvement to the documentation would be an addition to  
>>>> choice  2 (which I think is the preferred choice): "The global  
>>>> _impure_ptr  should be set to point to the thread-dependent  
>>>> _reent at every  thread switch by the OS".
>>>>
>>>
>>> Actually, I would say choice 4 is the preferred choice for threaded
>>> newlib.
>>>
>>>> Cheers,
>>>> Carl
>>>
>>>
>>>
>>>
>
>
>