From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57624) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WPx1C-0003Yd-Q5 for qemu-devel@nongnu.org; Tue, 18 Mar 2014 12:37:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WPx18-00067a-1c for qemu-devel@nongnu.org; Tue, 18 Mar 2014 12:37:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59341) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WPx17-00067R-OG for qemu-devel@nongnu.org; Tue, 18 Mar 2014 12:37:29 -0400 Message-ID: <53287643.4030504@redhat.com> Date: Tue, 18 Mar 2014 17:37:23 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <20140317215455.2f14b61f@redhat.com> <5327F398.7040509@siemens.com> <5327F771.7040205@redhat.com> <53282052.1020909@siemens.com> <20140318090043.3eba6b1a@redhat.com> <532859FD.4090907@siemens.com> <20140318122352.0e58240f@redhat.com> In-Reply-To: <20140318122352.0e58240f@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for-2.0?] target-i386: fix gdb debugging with large memory guests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino , Jan Kiszka Cc: peter.maydell@linaro.org, qemu-devel , afaerber@suse.de Il 18/03/2014 17:23, Luiz Capitulino ha scritto: > On Tue, 18 Mar 2014 15:36:45 +0100 > Jan Kiszka wrote: > >>>> Right, this belongs in the "if (env->hflags & HF_LMA_MASK)" block. >>>> >>>> And the subject or description should mention that >>>> x86_cpu_get_phys_page_debug was lacking support for 1G hugepages. >>> >>> To be honest, although the PS bit is set and that indicates a 1GB page, >>> I didn't know Linux does that. I thought Linux would use 4KB pages for >>> everything unless it's explicitly asked to use bigger pages. Also, note that >>> I was using gdb to debug really early kernel boot code (start_kernel()). >> >> I could imagine that Linux initially creates a giant identity mapping >> page table for the startup process and only later on switches to >> fine-grained tables of 4K and 2M pages. Giant pages still require >> hughtlbfs, IIRC. >> >>> >>> I'd feel more confident to have such a changelog after I find out where >>> exactly Linux sets that bit, but I won't have time in the next days. On the >>> other hand, the patch does fix the problem to me. >> >> Don't worry about Linux (the code should work with any OS anyway), just >> believe your reviewers. ;) Alternatively, check Intel IA32 SDM on page >> table structures. > > OK, so you want me to change the subject? Anything else for v2? You only need to move the new code into the "if (env->hflags & HF_LMA_MASK)", I think. The subject is ok. Paolo