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From: "Paul Koning" <Paul_Koning@Dell.com>
To: "Jie Zhang" <jie.zhang@analog.com>,
		"Michael Snyder" <msnyder@vmware.com>,
		"Dave Korn" <dave.korn.cygwin@googlemail.com>,
		<gdb@sourceware.org>
Subject: RE: Reset breakpoint after load?
Date: Fri, 22 Jan 2010 02:15:00 -0000	[thread overview]
Message-ID: <D8CEBB6AE9D43848BD2220619A43F32649F076@M31.equallogic.com> (raw)
In-Reply-To: <4B58D811.8070604@analog.com>

> On 01/22/2010 05:19 AM, Daniel Jacobowitz wrote:
> > On Thu, Jan 21, 2010 at 10:29:06AM -0800, Michael Snyder wrote:
> >>> On 19/01/2010 07:36, Jie Zhang wrote:
> >>>
> >>>> gdb-comm.exp sets breakpoints on exit and abort before load. The
> problem
> >>>> is that GDB tries to skip prologue according to what it reads
from
> >>>> memory, which might contain random data since the executable has
> not
> >>>> been loaded into memory. In my case, sometimes skip_prologue
might
> skip
> >>>> one or two more instructions, which happens to be an exception
> >>>> instruction and will trap the processor into an exception event
> loop
> >>>> after running the executable before hit the breakpoints.
> >
> > I've had this problem on a MIPS target, too.
> >
> I didn't notice this issue until recently a bug in toolchain linked in
> simulator libc for bare metal executable, which made this issue easily
> happen.
> 
> >> I don't believe that gdb can tell when the (remote) inferior
> >> is started.  All gdb knows is that target remote is started.
> >> Thus, if we connect to target remote and then load the image,
> >> there is an interval during which gdb will attempt to read
> >> the prologue bytes from un-initialized target memory.
> >>...

Yes, but... doesn't GDB take read-only data from the executable file
rather than from the target?  If so then it should not matter.  That's
what "set trust-readonly-sections" does.  Or is it off by default?  Turn
it on, that's good for performance anyway.

	paul


  reply	other threads:[~2010-01-22  2:15 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-19  7:36 Jie Zhang
2010-01-21 10:01 ` Dave Korn
2010-01-21 12:52   ` Jie Zhang
2010-01-21 18:29   ` Michael Snyder
2010-01-21 21:20     ` Daniel Jacobowitz
2010-01-21 22:41       ` Jie Zhang
2010-01-22  2:15         ` Paul Koning [this message]
2010-01-22  3:05           ` Jie Zhang
2010-01-22 11:46             ` Paul Koning
2010-01-22 13:46               ` Daniel Jacobowitz
2010-01-22 18:19               ` Michael Snyder
2010-01-21 22:35     ` Jie Zhang

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