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Re: [RFC stub-side break conditions 0/5] General info
- From: Eli Zaretskii <eliz at gnu dot org>
- To: luis_gustavo at mentor dot com
- Cc: gdb-patches at sourceware dot org
- Date: Fri, 06 Jan 2012 09:50:48 +0200
- Subject: Re: [RFC stub-side break conditions 0/5] General info
- References: <4F05B9FE.1000500@mentor.com>
- Reply-to: Eli Zaretskii <eliz at gnu dot org>
> Date: Thu, 05 Jan 2012 12:55:58 -0200
> From: Luis Machado <luis_gustavo@mentor.com>
>
> This patch series adds support and required machinery to enable
> breakpoint condition evaluation on the stub's side instead of solely in
> the host's side.
>
> When the evaluation is done on the stub's side, we eliminate all the
> useless stub -> GDB trap notifications that happen when the condition is
> false, potentially improving the speed of debugging on slower connections.
But the downside is that the stub has more work to do, and therefore
can potentially disrupt the timeline of the program being debugged.
Is this feature really worth it? How "slow" should a slow connection
be before this becomes a win? are there types of programs where this
mode should never be used for fear of interfering with the program's
timings?
> A new switch was added to make it possible to choose between gdb/stub
> evaluation modes: set/show breakpoint condition-evaluation. It defaults
> to "auto". "auto" means "gdb" whenever the stub can't handle breakpoint
> condition evaluation or when the expression can't be evaluated by the
> agent expression machinery. "auto" means "stub" when the remote stub
> supports evaluating conditions and if the expressions generate valid
> agent expression bytecodes.
Isn't it better to make the default be "off", i.e. keep the previous
modus operandi?