Re: Documentation reentrancy

[Carl Denzen Van <carl at vandenzen dot nl>]

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