From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Gboxq-0007K8-0b for qemu-devel@nongnu.org; Sun, 22 Oct 2006 21:50:54 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Gboxp-0007JX-0P for qemu-devel@nongnu.org; Sun, 22 Oct 2006 21:50:53 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Gboxo-0007JO-SC for qemu-devel@nongnu.org; Sun, 22 Oct 2006 21:50:52 -0400 Received: from [65.74.133.4] (helo=mail.codesourcery.com) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA:32) (Exim 4.52) id 1Gboxo-0006Ei-OR for qemu-devel@nongnu.org; Sun, 22 Oct 2006 21:50:53 -0400 From: Paul Brook Subject: Re: [Qemu-devel] qemu vs gcc4 Date: Mon, 23 Oct 2006 02:44:05 +0100 References: <45391B22.1050608@palmsource.com> <200610222127.08346.rob@landley.net> In-Reply-To: <200610222127.08346.rob@landley.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200610230244.06827.paul@codesourcery.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org > Basically, gcc changed in a way that broke qemu. There's been an open bug > report in gcc ever since, but the GCC developers really aren't interested > in backwards compatability. That's not entirely true. There are two problems: - qemu makes assumptions about the layout of the code gcc generates. This works by chance on older gcc. This effects all hosts, and is not a gcc bug. - qemu reserves several registers for its own use. On architecturally crippled hosts (ie. x86) this means we hit really obscure gcc bugs on x86 because gcc runs out of registers. This is a gcc bug, but is also relatively easy to workaround. Paul