* Paolo Bonzini (pbonz...@redhat.com) wrote: > > > On 26/05/2015 23:25, Christopher Covington wrote: > > On 05/25/2015 08:53 AM, Paolo Bonzini wrote: > >> > >> On 22/05/2015 13:12, Daniel P. Berrange wrote: > >>> In > >>> particular I don't see why we need to have a SATA controller and ISA/LPC > >>> bridge in every virt machine - root PCI bus only should be possible, as > >>> you > >>> can provide disks via virtio-blk or virtio-scsi and serial, parallel, > >>> mouse, > >>> floppy via PCI devices and/or by adding a USB bus in the cases where you > >>> really need one. > >> > >> I think removing the ISA/LPC bridge is hard. It includes the real-time > >> clock and fw_cfg, for example. > > > > Could VirtIO specified replacements make sense for these peripherals? > > Not really. virtio is too heavyweight and you'd be reinventing the > wheel unnecessarily.
I see reasons to replace some but not all these components; and there's no point in replacing the ISA/LPC bridge since it's got nothing at all in it. > For example, ARM's "-M virt" uses a pl011 block for the RTC, and also > uses fw_cfg. Another commonly used ISA device is the UART, for which > again -M virt uses a pl031. I don't see much point in replacing the simple PC uart with anything virtio; I can imagine that you might want to go down to something really trivial with non of the bells and whistles; but a UART is pretty simple. The PC RTC though, it's a bit of a disaster that's had 30 years of random cruft added into it to hold random things that should never have been there. Dave > > Paolo > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
