Patch that provides true single step for multi-threaded /proc based processes (Tru64 5.1A)

[Michael Snyder <msnyder at redhat dot com>]

Howdy everybody,


Hello Tony.

First off -- could you please post in plain text next time?
As you may be able to see, some of us use news readers that
don't handle mark-up languages.

Secondly, please excuse the long delay in reply.  Your patch looks
OK to me.  We will need a change-log entry, and then it can go in.

Thanks,

Michael Snyder
 In the company I work for, we use Tru64 5.1A as the main development
and deployment platform. The rather poor support for this platform in
gdb is the cause of problems and we have devoted some resources to find
a solve the most serious og these (as seem by us).Currently we use the
mdebugread patch as weel to handle the special sections in native Tru64
5.1A shared libraties.One problem we have been bitten by a number of
times was the lack of true single step support for multi-threaded
processes. As Tru64 5.1A is /proc based, the functions in question are
proc_run_process and procfs_resume. In these functions single step
support is only implemented for the new /proc API. Please note that we
use multi-CPU machine so we are bitten by this often!The following patch
will add support for the ioctl PIOCTRUN (if defined) in
proc_run_process.Please comment on this if you see anything wrong with
it.I don't know if the patch is general for all /proc based
architectures, but I currently expect so./tonny



     -- gdb/procfs.c-orig 2002-02-14
       02:57:36.000000000 +0100

     +++ gdb/procfs.c 2002-06-26 10:16:34.000000000 +0200@@ -1748,6
     +1748,30 @@win = (write (pi->ctl_fd, (char *) &cmd, sizeof
     (cmd)) == sizeof (cmd));}#else /* ioctl method */+#ifdef
     PIOCTRUN+ /*+ * If we single step AND the PIOCTRUN ioctl is
     supported, then use+ * this. This cures the problem when
     single stepping a+ * multi-threaded program, when all the
     other threads (than the+ * current single stepped one), may
     run free while single stepping.+ *+ * Note that only the
     PRSTEP flag is of interrest here (PRCFAULT and+ * PRCSIG are
     not allowed).+ */+ if (step) {+ /* Structure from proc(4) on
     Tru64 5.1A. */+ struct {+ long pr_count; /* number of threads
     to run */+ tid_t pr_error_thread; /* set by kernel if error is
     detected */+ struct prrun thread_1; /* prrun struct,
     containing thread ID of 1st thread to run in thread_1.pr_tid
     */+ } prrun;+ memset(&prrun, 0, sizeof (prrun));+
     prrun.pr_count = 1;+ prrun.thread_1.pr_flags = PRSTEP;+
     prrun.thread_1.pr_tid = pi->prstatus.pr_tid;+ win = (ioctl
     (pi->ctl_fd, PIOCTRUN, &prrun) >= 0);+ } else+#endif{prrun_t
     prrun;