Re: GDB support for thread-local storage

[Andrew Cagney <ac131313 at ges dot redhat dot com>]

> Andrew Cagney <ac131313@ges.redhat.com> writes:
>
> > > Doesn't libthread_db read `struct _pthread_descr_struct' from the
> > > linuxthreads library in the inferior, rather than knowing the layout
> > > itself?  So it's actually the inferior's linuxthreads library that
> > > describes its own structures' layout.
> > The structure layout will have been compiled into libthread-db.a.  It
> > implicitly knows the layout itself.
>
> I think you're wrong here.  Could you show me the code?
Sorry, you've lost me.

http://sources.redhat.com/cgi-bin/cvsweb.cgi/libc/linuxthreads/descr.h?rev=1.3&content-type=text/x-cvsweb-markup&cvsroot=glibc
> struct _pthread_descr_struct {
>   /* XXX Remove this union for IA-64 style TLS module */
>   union {
>     struct {
>       void *tcb;                /* Pointer to the TCB.  This is not always
>                                    the address of this thread descriptor.  */
>       union dtv *dtvp;
>       pthread_descr self;       /* Pointer to this structure */
>     } data;
>     void *__padding[16];
>   } p_header;
>   pthread_descr p_nextlive, p_prevlive;
>                                 /* Double chaining of active threads */
>   pthread_descr p_nextwaiting;  /* Next element in the queue holding the thr */
>   pthread_descr p_nextlock;     /* can be on a queue and waiting on a lock */
>   pthread_t p_tid;              /* Thread identifier */
>   int p_pid;                    /* PID of Unix process */
Note the use of ISA/ABI dependant data types such as ``int'', ``void 
*'', ...  As such they are implicitly included in and compiled into 
libhread-db.a

enjoy,
Andrew