Re: [PATCH] gdb.threads/process-dies-while-detaching: disable with software watchpoint

[Lancelot SIX <lsix@lancelotsix.com>]

On Sun, Sep 26, 2021 at 11:54:02AM +0200, Tom de Vries wrote:
> On 9/22/21 11:40 PM, Lancelot SIX wrote:
> > Hi,
> > 
> > I had a look at your patch, it is for sure a better approach than mine.
> > 
> > At some point you change the order between the 'continue_to_exit_bp' and
> > 'watch' commands when forcing software watchpoint.  Any reason not to
> > use the same order for both cases?
> > 
> 
> Yes, because sw watchpoints are slow.

I mean I totally understand why it makes sense to move the 'watch'
command after continue_to_exit_bp when using software watchpoints. The
question was more is there a reason not to do the same for hardware
watchpoints?  I do not expect any 'gain' from doing the same with
hardware assisted watchpoint except having something similar in both
cases.

> 
> > 	(gdb) PASS: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint:sw: watch globalvar
> > 	continue
> > 	Continuing.
> > 	[Thread 0x3fea68a150 (LWP 2358916) exited]
> > 	[...]
> > 	[Thread 0x3ff7ea5150 (LWP 2358889) exited]
> > 	KFAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint:sw: continue (timeout) (PRMS: gdb/28375)
> > 
> > This does not look like what you reported in PR28375.  I guess the
> > setup_kfail should be adjusted to account for the two way this test can
> > fail (I am not sure if they both come down to the same problem or not).
> > 
> 
> Is there a gdb prompt inbetween the PASS and KFAIL?

No. In the snippet I provided above, the '[...]' skips a bunch of
'[Thread 0xXXXXXXXXXX (LWP XXXXXXX) exited] ', and nothing else.

Looking into this I fixed an omission in the RISC-V prologue analyzer for which
I plan in submitting a patch later when I have found time to write a testcase
for it.  With this being fixed, the log for
gdb.threads/process-dies-while-detaching.exp becomes:

	watch globalvar
	Watchpoint 3: globalvar
	(gdb) PASS: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint:sw: watch globalvar
	continue
	Continuing.
	Cannot access memory at address 0x3ff7f2e324
	(gdb) KFAIL: gdb.threads/process-dies-while-detaching.exp: single-process: continue: watchpoint:sw: continue (PRMS: gdb/28375)
	UNSUPPORTED: gdb.threads/process-dies-while-detaching.exp: single-process: continue: hw watchpoint

I’ll continue to work on this when possible.

Best,
Lancelot.
> 
> Thanks,
> - Tom