From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 0/9] S390x KVM support Date: Thu, 22 Oct 2009 12:02:09 +0200 Message-ID: <4AE02DA1.8090500@redhat.com> References: <1255963059-10298-1-git-send-email-agraf@suse.de> <4ADDE7E3.9090601@de.ibm.com> <4AE0210D.9020409@redhat.com> <4AE02379.4090603@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Alexander Graf , qemu-devel , uli@suse.de, Carsten Otte , hare@suse.de, KVM list To: Carsten Otte Return-path: Received: from mx1.redhat.com ([209.132.183.28]:5941 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752449AbZJVKCO (ORCPT ); Thu, 22 Oct 2009 06:02:14 -0400 In-Reply-To: <4AE02379.4090603@de.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: On 10/22/2009 11:18 AM, Carsten Otte wrote: > >> I'd also appreciate an explanation of what this is all about. > The processor status word does contain various bits about the CPU's > state, such as interrupt mask bits, current address space, and the > current instruction address. The status is kept in the in-kernel sie > control block data structure and has so far only been mirrored into > kvm_run during exit_reason == s390_sieic exits because user space > needs to work on it. It was never part of get_regs/set_regs and > friends as performance optimization: it's needed on almost every exit, > having it in kvm_run saves doing syscalls. > The gdb stub requires an up-to-date copy at every exit, and therefore > the patch moves it out of the union and updates it at all userland exits. gdb is hardly performance critical. Is that the only reason for the change? -- error compiling committee.c: too many arguments to function