From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:55597) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SxWRC-0007IO-6k for qemu-devel@nongnu.org; Sat, 04 Aug 2012 00:58:07 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SxWRB-0004Ci-23 for qemu-devel@nongnu.org; Sat, 04 Aug 2012 00:58:06 -0400 Received: from audible.transient.net ([216.254.12.79]:57143) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1SxWRA-0004CG-Og for qemu-devel@nongnu.org; Sat, 04 Aug 2012 00:58:04 -0400 Date: Sat, 4 Aug 2012 04:58:01 +0000 From: Jamie Heilman Message-ID: <20120804045801.GD4231@cucamonga.audible.transient.net> References: <20120706092054.32044.37307.malonedeb@wampee.canonical.com> <20120725082553.26838.91137.malone@chaenomeles.canonical.com> <500FC6D2.2080000@msgid.tls.msk.ru> <500FEB84.6040409@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <500FEB84.6040409@redhat.com> Subject: Re: [Qemu-devel] [Bug 1021649] Re: qemu 1.1.0 waits for a keypress at boot List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Paul Brook , Michael Tokarev , "qemu-devel@nongnu.org" , Stefano Stabellini Avi Kivity wrote: > On 07/25/2012 02:12 PM, Stefano Stabellini wrote: > > On Wed, 25 Jul 2012, Michael Tokarev wrote: > >> Stefano, Paul, can you take a look please? > >> > >> https://bugs.launchpad.net/bugs/1021649 > > > > That is a very good bug triage that you did! > > > > However "main_loop_wait: block indefinitely" only increases the maximum > > select timeout of QEMU's main_loop. > > That mean that if one or more emulators have bugs and don't get > > notifications correctly they might hang. > > The reason why it only reproduces with nographic is that both sdl and vnc > > introduce a gui_timer that wakes QEMU up every 30ms. > > > > So the question is: why is kernel_irqchip=on required to repro the bug? > > It strikes me as a bug in kernel_irqchip that prevents QEMU from being > > waken up when it should. > > kernel_irqchip=on means that many guest timers and interrupt sources are > removed from qemu and implemented in the kernel, so qemu sees a lot less > wakeups and hangs. With kernel_irqchip=off the APIC or PIT wakes up > qemu, taking the place of the keypress. You're not implying the key press waking up qemu was a planned thing are you? Becuase it doesn't work at all when console is a -chardev pty device. With -machine kernel_irqchip=on -display none -chardev pty,... qemu simply hangs and consumes as much cpu as it can, attaching to the terminal and sending data does nothing. I'd hate to think that's the new normal. -- Jamie Heilman http://audible.transient.net/~jamie/