From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47401) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d8pSv-0003PC-BT for qemu-devel@nongnu.org; Thu, 11 May 2017 10:53:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d8pSs-0002E6-90 for qemu-devel@nongnu.org; Thu, 11 May 2017 10:53:17 -0400 Received: from mail-qk0-x22f.google.com ([2607:f8b0:400d:c09::22f]:35876) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1d8pSs-0002Dx-2o for qemu-devel@nongnu.org; Thu, 11 May 2017 10:53:14 -0400 Received: by mail-qk0-x22f.google.com with SMTP id u75so24270864qka.3 for ; Thu, 11 May 2017 07:53:13 -0700 (PDT) Date: Thu, 11 May 2017 10:53:12 -0400 From: Kevin O'Connor Message-ID: <20170511145312.GA822@morn.lan> References: <1494502528-12670-1-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1494502528-12670-1-git-send-email-pbonzini@redhat.com> Subject: Re: [Qemu-devel] [PATCH] target/i386: enable A20 automatically in system management mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org, anthony.xu@intel.com On Thu, May 11, 2017 at 01:35:28PM +0200, Paolo Bonzini wrote: > Ignore env->a20_mask when running in system management mode. Thanks Paolo. I don't think this patch will help SeaBIOS though. The SeaBIOS SMM handler doesn't do much - it doesn't even access ram above 1MiB. See SeaBIOS' code in src/fw/smm.c:handle_smi(). Instead, the SeaBIOS code does a cpu state backup/restore to switch into 32bit mode. I thought the A20 state would be part of that cpu backup/restore. However, looking at the Intel SDM docs now, it's not really clear to me how the processor "inhibits" A20 when in SMM mode - does it save/restore that state on SMI/RSM or does it have special logic to ignore A20 while in SMM mode? -Kevin