From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Meffa-0008NR-Id for qemu-devel@nongnu.org; Fri, 21 Aug 2009 21:45:26 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MeffW-0008NF-5V for qemu-devel@nongnu.org; Fri, 21 Aug 2009 21:45:26 -0400 Received: from [199.232.76.173] (port=36500 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MeffV-0008NC-VW for qemu-devel@nongnu.org; Fri, 21 Aug 2009 21:45:22 -0400 Received: from mail2.shareable.org ([80.68.89.115]:33661) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MeffV-0000R8-Aj for qemu-devel@nongnu.org; Fri, 21 Aug 2009 21:45:21 -0400 Date: Sat, 22 Aug 2009 02:45:15 +0100 From: Jamie Lokier Message-ID: <20090822014515.GA23926@shareable.org> References: <1250804057-29681-1-git-send-email-andre.przywara@amd.com> <20090821133330.GB4436@shareable.org> <4A8EADC9.3090106@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A8EADC9.3090106@amd.com> Subject: [Qemu-devel] Re: [PATCH] introduce kvm64 CPU List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Andre Przywara Cc: kvm@vger.kernel.org, avi@redhat.com, qemu-devel@nongnu.org Andre Przywara wrote: > If you happen to stuck with 32bit > (pity you!) then I agree that a kvm32 would be nice to have. > Will think about it... I know that 32-bit is a bit slower for some things due to register pressure (but it's a bit faster for some things due to less memory needed for pointers), and it's RAM is limited to about 3GB in practice, which affects some things but is plenty for others. I know it's a pain for KVM developers to support 32-bit hosts. And yes, it would be nice to run a 64-bit guest from time to time. But apart from being a bit slower, is there anything wrong with 32-bit x86s compared with 64-bit that justifies pity? The 32-bitness doesn't seem to be a handicap, only perhaps the expected amount of slowness for a laptop that's 2-3 years old, or a current netbook, compared with current desktops and servers. So I'm having a hard time understanding why 32-bitness is considered bad for KVM - why "pity"? Does it have any other real problems than not being able to emulate 64-bit guests that I should know about, or is it just a matter of distaste? -- Jamie