From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NFRg4-00074N-O4 for qemu-devel@nongnu.org; Tue, 01 Dec 2009 07:17:56 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NFRg0-00072C-U2 for qemu-devel@nongnu.org; Tue, 01 Dec 2009 07:17:56 -0500 Received: from [199.232.76.173] (port=35482 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NFRg0-00071s-CD for qemu-devel@nongnu.org; Tue, 01 Dec 2009 07:17:52 -0500 Received: from david.siemens.de ([192.35.17.14]:20834) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NFRg0-0001tG-0t for qemu-devel@nongnu.org; Tue, 01 Dec 2009 07:17:52 -0500 Message-ID: <4B15096A.5060801@siemens.com> Date: Tue, 01 Dec 2009 13:17:46 +0100 From: Jan Kiszka MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH 0/7] KVM SMP support, early version References: <1259256300-23937-1-git-send-email-glommer@redhat.com> <4B12B042.9020409@web.de> <5d6222a80911300342x4d29653as6c23acac598dec64@mail.gmail.com> <5d6222a80911300755o4fed5447w9ddae1abaccf7100@mail.gmail.com> <4B13F570.4030605@redhat.com> <5d6222a80911300847w2faa9d39nb2fc6ee3ccb9ccfd@mail.gmail.com> <4B140141.1040708@siemens.com> <4B1507AA.5050502@redhat.com> In-Reply-To: <4B1507AA.5050502@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Glauber Costa , Glauber Costa , "qemu-devel@nongnu.org" , "aliguori@us.ibm.com" Avi Kivity wrote: > On 11/30/2009 07:30 PM, Jan Kiszka wrote: >>>> No. But what's wrong with on_vcpu? >>>> >>> intrinsically racy. signal passing slow down things, etc. >>> >>> That said, as I've stated many times: I don't believe there's anything >>> fundamentally wrong with on_vcpu. But we might get benefits from a re-design >>> of things to avoid it whenever possible. (just like the vcpu_reset() >>> I've just posted) >>> >>> >> If you don't want immediate execution of update_guest_debug, save the >> state that shall be transferred, set some flag, and run the transfer >> before guest entry inside the vcpu threads (after putting the registers >> as older kernels may otherwise overwrite the flags register). Should >> work, may even avoid redundant calls during a gdb session. >> > > There's no guarantee the vcpu will ever exit to qemu, so you have to > signal the vcpu thread anyway. When you do that, you might as well load > the new state. Debugging is special here as it involves vmstop before you start playing with the debug settings. But I may also oversee some corner case right now. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux