gdb hanging in emacs

Ryan Johnson
Mon Apr 30 12:52:00 GMT 2012

On 29/04/2012 6:19 PM, Christopher Faylor wrote:
> On Sun, Apr 29, 2012 at 08:53:24AM -0400, Ken Brown wrote:
>> On 4/28/2012 3:58 PM, Ryan Johnson wrote:
>>> Hi all,
>>> I'm trying to use a home-built cross-gdb to do some remote debugging
>>> over tcp, but running gdb inside emacs doesn't work. M-x gud-gdb works
>>> fine, it's something wrong with the emacs integration. Unlike past times
>>> this has come up, the issue doesn't seem to be related to seg faults;
>>> the closest match I can find is from the emacs mailing list a while back
>>> [1], and involves a so-called "phase error." Basically, a large fraction
>>> of commands cause gud to hang in "[initializing...]" state for minutes
>>> or longer, apparently because it doesn't see what it expects and gets
>>> confused.
>>> The workaround to use 'file $BINARY' instead of specifying it at the
>>> command line avoids one problem, but simple things like 'set remotebaud
>>> 115200' also hang (unless added to a .gdbinit), and actually attempting
>>> to attach to the remote process similarly hangs forever in the
>>> initializing state. There is no CPU or disk utilization, and the command
>>> can't be interrupted with C-c C-c (though that does make it report a
>>> phase error before going back to hung). In some cases the "hang"
>>> resolves itself after about two minutes -- usually for simple commands
>>> like `set remotebaud' -- but more often than not, it's permanent. The
>>> behavior is also somewhat erratic, in the sense that the specific set of
>>> commands that hangs changes slowly over time and/or between invocations.
>>> So, two questions:
>>> 1. Has anyone else seen this, and if so, do they have any advice or
>>> workarounds?
>>> 2. Cygwin's official gdb doesn't seem to have any of these problems,
>>> though I can't test most of the commands, since it can't attach to the
>>> remote process. Is there some set of cygwin-specific patches I could
>>> borrow that make all the difference, or is my observation just coincidence?
>> Can't you just download the source for Cygwin's gdb and use that as the
>> starting point for your home-built cross-gdb?
> There is nothing magical in the Cygwin gdb source.  Any recent gdb source
> should be perfectly usable.
OK, I was just hoping there was some easy fix.


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