From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53267) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YUdgN-0004Df-7A for qemu-devel@nongnu.org; Sun, 08 Mar 2015 12:04:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YUdgJ-0001IR-P8 for qemu-devel@nongnu.org; Sun, 08 Mar 2015 12:03:59 -0400 Date: Sun, 8 Mar 2015 17:03:20 +0100 From: "Michael S. Tsirkin" Message-ID: <20150308160320.GA31757@redhat.com> References: <1425567322-8337-1-git-send-email-marcel@redhat.com> <1425567322-8337-11-git-send-email-marcel@redhat.com> <20150308104634.GA4714@redhat.com> <54FC2CA7.8080408@redhat.com> <20150308144754.GB29959@redhat.com> <54FC6943.3050201@redhat.com> <20150308152716.GD29959@redhat.com> <54FC6CB5.7060901@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54FC6CB5.7060901@redhat.com> Subject: Re: [Qemu-devel] [PATCH v3 for-2.3 10/24] hw/apci: add _PRT method for extra PCI root busses List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Marcel Apfelbaum Cc: kraxel@redhat.com, quintela@redhat.com, seabios@seabios.org, qemu-devel@nongnu.org, agraf@suse.de, alex.williamson@redhat.com, kevin@koconnor.net, qemu-ppc@nongnu.org, hare@suse.de, imammedo@redhat.com, amit.shah@redhat.com, pbonzini@redhat.com, leon.alrae@imgtec.com, aurelien@aurel32.net, rth@twiddle.net On Sun, Mar 08, 2015 at 05:37:25PM +0200, Marcel Apfelbaum wrote: > On 03/08/2015 05:27 PM, Michael S. Tsirkin wrote: > >On Sun, Mar 08, 2015 at 05:22:43PM +0200, Marcel Apfelbaum wrote: > >>On 03/08/2015 04:47 PM, Michael S. Tsirkin wrote: > >>>On Sun, Mar 08, 2015 at 01:04:07PM +0200, Marcel Apfelbaum wrote: > >>>>On 03/08/2015 12:46 PM, Michael S. Tsirkin wrote: > >>>>>On Thu, Mar 05, 2015 at 04:55:08PM +0200, Marcel Apfelbaum wrote: > >>>>>>Signed-off-by: Marcel Apfelbaum > >>>>> > >>>>>some ideas for cleaning this up. > >>>>>there's more here btw. > >>>>> > >>>>>>--- > >>>>>> hw/i386/acpi-build.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > >>>>>> 1 file changed, 78 insertions(+) > >>>>>> > >>>>>>diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c > >>>>>>index e5709e8..f0401d2 100644 > >>>>>>--- a/hw/i386/acpi-build.c > >>>>>>+++ b/hw/i386/acpi-build.c > >>>>>>@@ -664,6 +664,83 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus, > >>>>>> aml_append(parent_scope, method); > >>>>>> } > >>>>>> > >>>>>>+static Aml *build_prt(void) > >>>>>>+{ > >>>>>>+ Aml *method, *pkg, *if_ctx, *while_ctx; > >>>>>>+ > >>>>>>+ method = aml_method("_PRT", 0); > >>>>>>+ > >>>>>>+ aml_append(method, aml_store(aml_package(128), aml_local(0))); > >>>>>>+ aml_append(method, aml_store(aml_int(0), aml_local(1))); > >>>>>>+ while_ctx = aml_while(aml_lless(aml_local(1), aml_int(128))); > >>>>>>+ { > >>>>>>+ aml_append(while_ctx, > >>>>>>+ aml_store(aml_shiftright(aml_local(1), aml_int(2)), aml_local(2))); > >>>>>>+ aml_append(while_ctx, > >>>>>>+ aml_store(aml_and(aml_add(aml_local(1), aml_local(2)), aml_int(3)), > >>>>>>+ aml_local(3))); > >>>>> > >>>>> > >>>>>As an example, you can have > >>>>> > >>>>>Aml *i = aml_local(1); > >>>>>Aml *mask = aml_local(2); > >>>>Hi Michael, > >>>> > >>>>Thank you for the tip, the implementation is ready > >>>>and I'll submit it right away. > >>> > >>>So, one thing that's problematic here is that > >>>expected files need to be examined manually. > >>Only if pxb-device is added, otherwise they remain the same. > >>So by default, make check remains unchanged. > >>>How about a three-stage approach: > >>> > >>>1. move _PRT out from DSDT - e.g. to a separate ssdt, > >>> update expected files. > >>> One way to do this is to first revert > >>> commit 4ec8d2b3f54dd1dcd9e2a80e529feff4e2603288 > >>> Author: Igor Mammedov > >>> pc: acpi-build: drop remaining ssdt_misc template > >>>2. rewrite the new SSDT in C, > >>> produce an otherwise identical code. > >>> make check will catch errors > >>>3. reuse code from (2) for extra roots. > >> > >>I am aware of this and I was planning to do that on top of this series. > >>Four reasons for this: > >> 1. As stated before, it does not affect make check because this code > >> affects the ACPI table only if pxb-device is present. > >> 2. The _PRT is not *exactly* the same, bus 0's _PRT has an extra "if" for > >> the power-management device than needs needs SCI > >> 3. The series is already big, I prefer attacking this as a new enhancement: > >> "Dynamically create bus 0 _PRT" > >> 4. QEMU 2.3 is approaching, I don't want o diverge now > >> > >> > >>Thanks, > >>Marcel > > > >Meanwhile 2.3 will have two almost identical copies of _PRT? > >I don't think that's a good idea. > The are 2 *different* _PRTs for 2 different hw components. > The look the same only because I *preferred* them to look almost the same, > I could implement it differently. > There is actually nothing common about > 1. PIIX host bridge _PRT implemented statically > 2. pcb-device _PRT implemented in code. > > What is true is the series makes easier to implement dynamic _PRT > for any device, including PIIX host bridge. It doesn't mean we have two. > > Actually we need to think about using the same code, because changing it > would influence both devices. > > I really don't think they are related. > Thanks, > Marcel Come on, the same argument would make us duplicate almost any block of code. Copy-pasting always seems safer and faster than reusing, until you have to fix a bug in multiple places. > > > > >>> > [...]