From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59789) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WPx9Q-0000Do-3t for qemu-devel@nongnu.org; Tue, 18 Mar 2014 12:46:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WPx9K-0000jq-9f for qemu-devel@nongnu.org; Tue, 18 Mar 2014 12:46:04 -0400 Received: from david.siemens.de ([192.35.17.14]:58696) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WPx9J-0000jk-UO for qemu-devel@nongnu.org; Tue, 18 Mar 2014 12:45:58 -0400 Message-ID: <53287842.2080102@siemens.com> Date: Tue, 18 Mar 2014 17:45:54 +0100 From: Jan Kiszka 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> <53287643.4030504@redhat.com> In-Reply-To: <53287643.4030504@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 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: Paolo Bonzini , Luiz Capitulino Cc: peter.maydell@linaro.org, qemu-devel , afaerber@suse.de On 2014-03-18 17:37, Paolo Bonzini wrote: > 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. Yes. Subject is fine, a reference to GB pages in the description would be nice-to-have. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux