From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58850) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SW7Dr-00060o-0q for qemu-devel@nongnu.org; Sun, 20 May 2012 10:35:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SW7Do-0003fp-J8 for qemu-devel@nongnu.org; Sun, 20 May 2012 10:35:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:8676) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SW7Do-0003fV-Bn for qemu-devel@nongnu.org; Sun, 20 May 2012 10:35:00 -0400 Message-ID: <4FB90110.1000003@redhat.com> Date: Sun, 20 May 2012 17:34:56 +0300 From: Avi Kivity MIME-Version: 1.0 References: <1337504620-20378-1-git-send-email-gleb@redhat.com> <1337504620-20378-3-git-send-email-gleb@redhat.com> <4FB8D933.5070800@redhat.com> <20120520121539.GJ10209@redhat.com> <4FB8E3FA.2040408@redhat.com> <20120520123633.GL10209@redhat.com> <4FB8E7C6.5090000@redhat.com> <20120520125936.GM10209@redhat.com> <4FB8F3F5.6010903@redhat.com> <20120520135733.GN10209@redhat.com> In-Reply-To: <20120520135733.GN10209@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/3] Get system state configuration from QEMU and patch DSDT with it. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: seabios@seabios.org, qemu-devel@nongnu.org On 05/20/2012 04:57 PM, Gleb Natapov wrote: > On Sun, May 20, 2012 at 04:39:01PM +0300, Avi Kivity wrote: > > On 05/20/2012 03:59 PM, Gleb Natapov wrote: > > > > > > > > > > > > > > > > Do we actually have to patch the DSDT? Or can _S3 etc be made into > > > > > > > > functions instead? (and talk to the bios, or even to fwcfg directly?) > > > > > > > > > > > > > > > We better not talk to fwcfg after OSPM is started since this is firmware > > > > > > > confing interface. > > > > > > > > > > > > Why not? The OS isn't going to talk to it, so we can have a driver in ACPI. > > > > > > > > > > > The OS is going to talk to it since the OS is the one who interprets > > > > > AML. > > > > > > > > I meant, not directly. So the driver in ACPI has exclusive access. > > > > > > > What's the difference? > > > > ACPI is firmware, not OS. > AML is a data provided by firmware. AML's runtime is different from firmware's. It's still firmware. > > > > > > > > It's an alternative to patching AML. Sure it takes some effort to write > > > > the driver, but afterwards we can modify the guest behaviour more > > > > easily. One possible client is -M old, so you can revert to previous > > > > behaviour depending on fwcfg data. > > > -M old is easy to support with the current patch. You just set new > > > properties to compatibility values. The code is written with this in > > > mind. And this is not an alternative to patching AML as I am trying to > > > explain to you below. You can eliminate patching of s4 value, but that's > > > it, you still need to patch out _S3/_S4 names. > > > > What about > > > > If (Fcfg(...)) { > > Method()... > > } > > > > ? > syntax error, unexpected PARSEOP_IF Unfortunately the ACPI spec forbids this construct, so either patching or double complication is necessary. > > > > (i.e.. define the method conditionally at runtime) > > > > > > > > > > > > > (we don't need a driver in AML to avoid patching, we can have AML talk > > > > to the bios and the bios drive fwcfg; but I think we'll find uses for a > > > > driver). > > > I am not sure what you mean. AML can't talk to the bios. It can read > > > values that bios put somewhere. > > > > That's what I meant - communicate through memory. > > > What's the benefit? The patching is still needed. You need to pass > address of OperationRegion() to AML. You can do it either by patching or > by creating OperationRegion() code dynamically. Or it can be a fixed address in low memory, or a scratch register in hardware. > > > > I do not see advantage of this method > > > and it requires patching still. > > > > For the existence of the names? Yes, if we can't avoid it it's a > > problem. But if we can avoid patching, we should. > > > If we can, we should, but we can't as far as I see. The patching was here long before > this patch. I agree we probably can't. -- error compiling committee.c: too many arguments to function