From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=43940 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ONPjI-0008Ms-TZ for qemu-devel@nongnu.org; Sat, 12 Jun 2010 08:22:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1ONPjH-0002kh-Tr for qemu-devel@nongnu.org; Sat, 12 Jun 2010 08:22:29 -0400 Received: from hall.aurel32.net ([88.191.82.174]:58514) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1ONPjH-0002kd-PZ for qemu-devel@nongnu.org; Sat, 12 Jun 2010 08:22:27 -0400 Resent-Message-ID: <20100612122214.GB1390@ohm.aurel32.net> Resent-To: rth@twiddle.net, qemu-devel@nongnu.org, agraf@suse.de Date: Sat, 12 Jun 2010 13:57:09 +0200 From: Aurelien Jarno Subject: Re: [Qemu-devel] [PATCH 15/35] tcg-s390: Query instruction extensions that are installed. Message-ID: <20100612115709.GL3008@ohm.aurel32.net> References: <1275678883-7082-1-git-send-email-rth@twiddle.net> <1275678883-7082-16-git-send-email-rth@twiddle.net> <20100610102815.GM26968@volta.aurel32.net> <4C1164ED.7020403@twiddle.net> <20100611080634.GP26968@volta.aurel32.net> <4C123528.6050500@twiddle.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <4C123528.6050500@twiddle.net> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: qemu-devel@nongnu.org, agraf@suse.de On Fri, Jun 11, 2010 at 06:07:52AM -0700, Richard Henderson wrote: > On 06/11/2010 01:06 AM, Aurelien Jarno wrote: > > What's the difference between FACILITY_ZARCH and FACILITY_ZARCH_ACTIVE, > > as both are actually flagged together. My guess is that > > FACILITY_ZARCH_ACTIVE is needed in 64-bit mode, why FACILITY_ZARCH is > > only needed for a possible future 32-bit mode. Is it correct? > > Loosely, > > ZARCH is set when the system is 64-bit capable, whether or not it is active. > The OS would check this bit at startup if it wanted to change modes. This > bit isn't really interesting to us in userspace. > > ZARCH_ACTIVE is set when the system is in 64-bit mode, i.e. you've booted > with a 64-bit kernel. Note that this says nothing about the address > decoding mode -- this bit can be set while the PSW is set for 31-bit > address translation, e.g. running a 32-bit program on a 64-bit kernel. > So in short we never use ZARCH in QEMU, so we probably don't want to have this #define, nor add it at the same time as FACILITY_ZARCH_ACTIVE. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurelien@aurel32.net http://www.aurel32.net