From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35519) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ysaff-0001o3-05 for qemu-devel@nongnu.org; Wed, 13 May 2015 13:42:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ysafb-0004ww-Kx for qemu-devel@nongnu.org; Wed, 13 May 2015 13:42:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42273) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ysafb-0004wh-GR for qemu-devel@nongnu.org; Wed, 13 May 2015 13:42:11 -0400 Date: Wed, 13 May 2015 18:42:04 +0100 From: "Daniel P. Berrange" Message-ID: <20150513174204.GS23627@redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefano Stabellini Cc: pbonzini@redhat.com, xen-devel@lists.xensource.com, mst@redhat.com, qemu-devel@nongnu.org, rth@twiddle.net On Wed, May 13, 2015 at 06:29:46PM +0100, Stefano Stabellini wrote: > Do not emulate a floppy drive if no drives are supposed to be present. > > This fixes the behavior of -nodefaults, that should remove the floppy > drive (see docs/qdev-device-use.txt:Default Devices), but actually > doesn't. Technically that doc is just refering to the disablement of the primary floppy drive, as opposed to the floppy controller. The floppy controller itself is really a built-in device that is defined as part of the machine type, along with the various other platform devices hanging off the PIIX and ISA brige. > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index a8e6be1..c9f50b3 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -1410,6 +1410,7 @@ void pc_basic_device_init(ISABus *isa_bus, qemu_irq *gsi, > qemu_irq *cpu_exit_irq; > MemoryRegion *ioport80_io = g_new(MemoryRegion, 1); > MemoryRegion *ioportF0_io = g_new(MemoryRegion, 1); > + bool floppy_exist; > > memory_region_init_io(ioport80_io, NULL, &ioport80_io_ops, NULL, "ioport80", 1); > memory_region_add_subregion(isa_bus->address_space_io, 0x80, ioport80_io); > @@ -1487,10 +1488,17 @@ void pc_basic_device_init(ISABus *isa_bus, qemu_irq *gsi, > cpu_exit_irq = qemu_allocate_irqs(cpu_request_exit, NULL, 1); > DMA_init(0, cpu_exit_irq); > > + *floppy = NULL; > + floppy_exist = false; > for(i = 0; i < MAX_FD; i++) { > fd[i] = drive_get(IF_FLOPPY, 0, i); > + if (fd[i] != NULL) { > + floppy_exist = true; > + } > + } > + if (floppy_exist) { > + *floppy = fdctrl_init_isa(isa_bus, fd); > } > - *floppy = fdctrl_init_isa(isa_bus, fd); > } This results in a guest ABI change when updating QEMU, because the floppy controller will disappear for existing guests. This is liable to break guests upon migration. If we want to be able to disable the floppy controller itself, in addition to the floppy drives, then we'd likely need to define a property against the machine type to allow its existence to be toggled on/off. We'd then need to at least make sure the existing machine types defaulted to on, if we decided that new machine types should default to off. Libvirt would also need to gain the ability to represent the existance of the floppy controller and allow it to be turned on / off explicitly. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Daniel P. Berrange" Subject: Re: [PATCH] Do not emulate a floppy drive when -nodefaults Date: Wed, 13 May 2015 18:42:04 +0100 Message-ID: <20150513174204.GS23627@redhat.com> References: Reply-To: "Daniel P. Berrange" Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org To: Stefano Stabellini Cc: pbonzini@redhat.com, xen-devel@lists.xensource.com, mst@redhat.com, qemu-devel@nongnu.org, rth@twiddle.net List-Id: xen-devel@lists.xenproject.org On Wed, May 13, 2015 at 06:29:46PM +0100, Stefano Stabellini wrote: > Do not emulate a floppy drive if no drives are supposed to be present. > > This fixes the behavior of -nodefaults, that should remove the floppy > drive (see docs/qdev-device-use.txt:Default Devices), but actually > doesn't. Technically that doc is just refering to the disablement of the primary floppy drive, as opposed to the floppy controller. The floppy controller itself is really a built-in device that is defined as part of the machine type, along with the various other platform devices hanging off the PIIX and ISA brige. > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index a8e6be1..c9f50b3 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -1410,6 +1410,7 @@ void pc_basic_device_init(ISABus *isa_bus, qemu_irq *gsi, > qemu_irq *cpu_exit_irq; > MemoryRegion *ioport80_io = g_new(MemoryRegion, 1); > MemoryRegion *ioportF0_io = g_new(MemoryRegion, 1); > + bool floppy_exist; > > memory_region_init_io(ioport80_io, NULL, &ioport80_io_ops, NULL, "ioport80", 1); > memory_region_add_subregion(isa_bus->address_space_io, 0x80, ioport80_io); > @@ -1487,10 +1488,17 @@ void pc_basic_device_init(ISABus *isa_bus, qemu_irq *gsi, > cpu_exit_irq = qemu_allocate_irqs(cpu_request_exit, NULL, 1); > DMA_init(0, cpu_exit_irq); > > + *floppy = NULL; > + floppy_exist = false; > for(i = 0; i < MAX_FD; i++) { > fd[i] = drive_get(IF_FLOPPY, 0, i); > + if (fd[i] != NULL) { > + floppy_exist = true; > + } > + } > + if (floppy_exist) { > + *floppy = fdctrl_init_isa(isa_bus, fd); > } > - *floppy = fdctrl_init_isa(isa_bus, fd); > } This results in a guest ABI change when updating QEMU, because the floppy controller will disappear for existing guests. This is liable to break guests upon migration. If we want to be able to disable the floppy controller itself, in addition to the floppy drives, then we'd likely need to define a property against the machine type to allow its existence to be toggled on/off. We'd then need to at least make sure the existing machine types defaulted to on, if we decided that new machine types should default to off. Libvirt would also need to gain the ability to represent the existance of the floppy controller and allow it to be turned on / off explicitly. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|