From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:35557) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SFj89-0003GO-5S for qemu-devel@nongnu.org; Thu, 05 Apr 2012 05:37:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SFj7w-0002cN-Eg for qemu-devel@nongnu.org; Thu, 05 Apr 2012 05:37:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24426) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SFj7w-0002bA-6g for qemu-devel@nongnu.org; Thu, 05 Apr 2012 05:37:12 -0400 Date: Thu, 5 Apr 2012 12:37:01 +0300 From: "Michael S. Tsirkin" Message-ID: <20120405093701.GD28229@redhat.com> References: <20120405050848.31461.10826.stgit@bling.home> <20120405055113.31461.45258.stgit@bling.home> <4F7D55FE.1070407@redhat.com> <20120405090444.GB28229@redhat.com> <20120405091237.GC11204@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120405091237.GC11204@redhat.com> Subject: Re: [Qemu-devel] [PATCH 2/5] acpi_piix4: Only allow writes to PCI hotplug eject register List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: aliguori@us.ibm.com, jbaron@redhat.com, qemu-devel@nongnu.org, yamahata@valinux.co.jp, Alex Williamson , kraxel@redhat.com, pbonzini@redhat.com, Igor Mammedov , aurelien@aurel32.net On Thu, Apr 05, 2012 at 12:12:37PM +0300, Gleb Natapov wrote: > On Thu, Apr 05, 2012 at 12:04:44PM +0300, Michael S. Tsirkin wrote: > > On Thu, Apr 05, 2012 at 10:21:18AM +0200, Igor Mammedov wrote: > > > On 04/05/2012 07:51 AM, Alex Williamson wrote: > > > >This is never read. We can also derive bus from the write handler, > > > >making this more inline with the other callbacks. Note that > > > >pciej_write was actually called with (PCIBus *)dev->bus, which is > > > >cast as a void* allowing us to pretend it's a BusState*. Fix this > > > >so we don't depend on the BusState location within PCIBus. > > > > > > > >Signed-off-by: Alex Williamson > > > >--- > > > > > > > > docs/specs/acpi_pci_hotplug.txt | 2 +- > > > > hw/acpi_piix4.c | 14 ++++---------- > > > > 2 files changed, 5 insertions(+), 11 deletions(-) > > > > > > > >diff --git a/docs/specs/acpi_pci_hotplug.txt b/docs/specs/acpi_pci_hotplug.txt > > > >index 1e2c8a2..1e61d19 100644 > > > >--- a/docs/specs/acpi_pci_hotplug.txt > > > >+++ b/docs/specs/acpi_pci_hotplug.txt > > > >@@ -28,7 +28,7 @@ PCI device eject (IO port 0xae08-0xae0b, 4-byte access): > > > > ---------------------------------------- > > > > > > > > Used by ACPI BIOS _EJ0 method to request device removal. One bit per slot. > > > >-Reads return 0. > > > >+Read-only. > > > Write-only perhaps? > > > > Yes, let's also specify what happens in practice. > No we shouldn't. > > > I think it is 'Guest should never read this register, in practice > > 0 is returned'. > > > In practice kitten die for each read. Unspecified behaviour is > unspecified. Why, what are you worried about? I just want to document what we do. The reason I want to specify behaviour on read is because down the road we might want to return something here. Our lives will be easier if we have a document which we can read and figure out what old qemu did. > -- > Gleb.