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Subject: Re: [virtio-comment] comment on pci section
On Wed, Jan 29, 2014 at 04:38:58PM +1030, Rusty Russell wrote: > "Michael S. Tsirkin" <email@example.com> writes: > > Two comments received from a co-worker: > > > > 3.1 "The device MUST NOT consume buffers before DRIVER_OK ..." - I > > personally > > would like to see also something like: "device must not generate > > interrupts if > > DRIVER_OK is not set” to better handle power management transitions. > > That addition seems to make sense, but I don't understand the reference > to power management transitions? Well - ATM we do things like suspend by device reset and re-initialization, right? I'm guessing during e.g. resume it's important not to get interrupts too early. I'll check. Hmm actually we have a chapter about initialization but not cleanup. Might be a good addition. Also, I note that QEMU implemented master abort bit by clearing DRIVER_OK - AFAIK useful to stop device in a standard way if driver malfunctions. Also with QEMU you can clear DRIVER_OK and this stops the device. I wonder if someone uses this. > > 126.96.36.199.1. > > Must clarify that all devices MUST support all cfg_type values 1-5. > > This way BIOS can limit type 5 exclusively and drivers don't > > need to add support for type 5. > > The word "support" here is unclear to me. Are you saying that a device > MUST offer a VIRTIO_PCI_CAP_PCI_CFG value? Something like: > > Drivers MUST offer at least one capability of each type. Exactly. Except > Thanks, > Rusty.