From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53671) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a3nno-0005pb-TT for qemu-devel@nongnu.org; Tue, 01 Dec 2015 11:29:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a3nnn-0000zZ-KB for qemu-devel@nongnu.org; Tue, 01 Dec 2015 11:29:16 -0500 Received: from mail-vk0-x232.google.com ([2607:f8b0:400c:c05::232]:36340) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a3nnn-0000zE-9J for qemu-devel@nongnu.org; Tue, 01 Dec 2015 11:29:15 -0500 Received: by vkay187 with SMTP id y187so7185211vka.3 for ; Tue, 01 Dec 2015 08:29:15 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1448986767-28016-1-git-send-email-rth@twiddle.net> References: <1448986767-28016-1-git-send-email-rth@twiddle.net> From: Peter Maydell Date: Tue, 1 Dec 2015 16:28:55 +0000 Message-ID: Content-Type: text/plain; charset=UTF-8 Subject: Re: [Qemu-devel] [PATCH for-2.5] tcg: Increase the highwater reservation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: QEMU Developers , Aurelien Jarno On 1 December 2015 at 16:19, Richard Henderson wrote: > If there are a lot of guest memory ops in the TB, the amount of > code generated by tcg_out_tb_finalize could be well more than 1k. > In the short term, increase the reservation larger than any TB > seen in practice. > > Reported-by: Aurelien Jarno > Signed-off-by: Richard Henderson > --- > > Reported and discussed with Aurelien on IRC yesterday. This seems > to be the easiest fix for the upcoming release. I will fix this > properly (by modifying every backend's finalize routines) for 2.6. What would be the result of our hitting this bug? I ask because there's a report on qemu-discuss about a qemu-i386-on-ARM-host bug: http://lists.nongnu.org/archive/html/qemu-discuss/2015-11/msg00042.html and the debug log (http://www.mediafire.com/download/ge611be9vbebbw7/qemu.log) suggests we're segfaulting in translation on the TB shortly after we (successfully) translate a TB whose final 'out' size is 1100 and which has 64 guest writes in it. So I'm wondering if that's actually the same bug this is fixing... thanks -- PMM