svn commit: r354239 - head/contrib/gdb/gdb

[John Baldwin]

On 11/1/19 12:26 PM, luporl wrote:
> Well, after evaluating remote kernel debugging through serial port, on
> amd64, I've run into several issues while using latest ports gdb/kgdb.
> I don't remember all of them, but were things like step/next not always
> working, connection being lost, and similar things.
> OTOH, /usr/libexec/kgdb worked fine and reliably, although older and more
> limited.
> This is probably due to some incompatibility in GDB Remote Serial Protocol,
> between the kernel backend and newer GDB from ports.
> 
> So, that's why I chose to use /usr/libexec/kgdb while fixing/enabling
> remote debugging on PPC64, because it works reasonably well, and I could
> focus on testing/fixing other parts first.
> With only this change on gdb, it is now possible to use it to test some
> basic functionality, like remote debugger attach, backtrace and data
> inspection.
> 
> My goal is not to fix every issue in /usr/libexec/kgdb, but just to get the
> basics working, to then move on and switch to ports' GDB.

What's odd about this commit is it only affects userland binaries, not the
kernel, so a bit odd for kgdb, especially since the old kgdb in the tree
doesn't include user support IIRC, only kernel bits (in modern gdb, kgdb
is just a wrapper, and you can use 'target vmcore' from within gdb itself
against a crash dump, etc.)

-- 
John Baldwin