From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MR2T3-0002Cf-T0 for qemu-devel@nongnu.org; Wed, 15 Jul 2009 07:16:09 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MR2Sy-0002C5-BI for qemu-devel@nongnu.org; Wed, 15 Jul 2009 07:16:08 -0400 Received: from [199.232.76.173] (port=40336 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MR2Sy-0002C0-4y for qemu-devel@nongnu.org; Wed, 15 Jul 2009 07:16:04 -0400 Received: from mx2.redhat.com ([66.187.237.31]:44150) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MR2Sx-0006ts-N4 for qemu-devel@nongnu.org; Wed, 15 Jul 2009 07:16:04 -0400 Date: Wed, 15 Jul 2009 14:14:01 +0300 From: Gleb Natapov Subject: Re: [Qemu-devel] [PATCH] monitor: Add port write command Message-ID: <20090715111401.GH28046@redhat.com> References: <4A5C3FBB.10306@siemens.com> <200907142030.27019.paul@codesourcery.com> <20090715073451.GF28046@redhat.com> <200907151114.21482.paul@codesourcery.com> <4A5DB231.7040109@siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A5DB231.7040109@siemens.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Anthony Liguori , Paul Brook , qemu-devel@nongnu.org On Wed, Jul 15, 2009 at 12:40:49PM +0200, Jan Kiszka wrote: > Paul Brook wrote: > >>> I'd be reluctant to expose the savevm state to the user. > >>> > >>> For debugging qemu I don't see it providing any real benefit over firing > >>> up GDB and poking directly at the device directly. > >> Not all environments where you need to debug things have gdb, qemu > >> sources or even non striped qemu binary. > > > > If you don't have qemu sources than I really don't care. By definition you're > > not going to be able to do anything useful even if you do figure out what the > > problem is. Note that there's no requirement that you run gdb on the target > > itself. Remote debug (e.g. via gdbserver on linux) is a well established > > technique. > > > > Likewise for debugging stripped production binaries, my answer is "don't do > > that". There are very rare cases where a bug goes away on a debug build, but > > in those cases any instrumentation you add is also liable to make the bug go > > away. > > Again, having to debug qemu itself when all you want is some additional > information about the emulated hardware state while debugging a guest > seems like overkill to me. Imagine you are attached to qemu's gdbstub > and stopped the guest that has some issue using, say, the apic. And now > imagine you could simply issue e.g. > > (gdb) monitor devstate apic.1 > apicbase=... > tpr=... > icr={..., ... } > lvt={..., ... } > ... > > That would provide you a nice picture of the virtual hardware state > without the need to fire up and operate a second gdb just to obtain this > data. And manipulating some lvt register would only be a trivial > additional monitor command away. > apic/ioapic is important enough to warrant "info apic" "info ioapic" commands. -- Gleb.