From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1N0uVv-0007Ne-Io for qemu-devel@nongnu.org; Thu, 22 Oct 2009 06:03:23 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1N0uVr-0007N3-SX for qemu-devel@nongnu.org; Thu, 22 Oct 2009 06:03:23 -0400 Received: from [199.232.76.173] (port=47144 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1N0uVr-0007Ms-MD for qemu-devel@nongnu.org; Thu, 22 Oct 2009 06:03:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:65040) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1N0uVr-0006hf-3T for qemu-devel@nongnu.org; Thu, 22 Oct 2009 06:03:19 -0400 Message-ID: <4AE02DE2.7010803@redhat.com> Date: Thu, 22 Oct 2009 12:03:14 +0200 From: Avi Kivity MIME-Version: 1.0 References: <1255963059-10298-1-git-send-email-agraf@suse.de> <4ADDE7E3.9090601@de.ibm.com> <4AE0210D.9020409@redhat.com> <98DC9E4C-7FFA-4F05-A2E8-0B5DF546891C@suse.de> <4AE02B8E.6070202@redhat.com> <8D99A5FD-8A2E-4DA9-90A5-6935F677F9FD@suse.de> In-Reply-To: <8D99A5FD-8A2E-4DA9-90A5-6935F677F9FD@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH 0/9] S390x KVM support List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: Carsten Otte , KVM list , Carsten Otte , qemu-devel , hare@suse.de On 10/22/2009 11:55 AM, Alexander Graf wrote: > > On 22.10.2009, at 11:53, Avi Kivity wrote: > >> On 10/22/2009 11:11 AM, Alexander Graf wrote: >>>> Doesn't this break backward compatibility by changing the structure? >>>> >>>> Best to put it after the union (and as a copy, so userspace that >>>> expects the previous location still works). If you're reading it >>>> from the kernel, also need a way to tell the kernel which copy to >>>> read from. >>>> >>>> Also advertise with a KVM_CAP. >>> >>> >>> I don't think we need to go through the hassle here. There is >>> effectively no user of that code for now and the ABI is considered >>> unstable. >> >> At the very least we need a KVM_CAP so qemu knows to fail on older >> kernels. > > Hm. Oh well :-). It can't hurt to have yet another CAP, right? > >>>> I'd also appreciate an explanation of what this is all about. >>> >>> Explanation in the code or explanation in an email reply? >> >> >> email. I assume s390 hackers would understand why the psw needs to >> be exposed to qemu on every exit. This is mostly for my personal >> interest. > > PSW = (eflags << 32) | pc; > > :-) > > Before that patch it was only synced with the "vmcb" on special > userspace handled intercepts, now it's synced on every exit to userspace. Right, but why? x86 qemu doesn't care about either pc or eflags (with in-kernel irqchip, which s390 essentially is). -- error compiling committee.c: too many arguments to function