Messages in this thread | | | Date | Thu, 30 Apr 2020 16:04:46 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: [RFC/PATCH 1/1] virtio: Introduce MMIO ops |
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* Will Deacon <will@kernel.org> [2020-04-30 11:14:32]:
> > +#ifdef CONFIG_VIRTIO_MMIO_OPS > > > > +static struct virtio_mmio_ops *mmio_ops; > > + > > +#define virtio_readb(a) mmio_ops->mmio_readl((a)) > > +#define virtio_readw(a) mmio_ops->mmio_readl((a)) > > +#define virtio_readl(a) mmio_ops->mmio_readl((a)) > > +#define virtio_writeb(val, a) mmio_ops->mmio_writeb((val), (a)) > > +#define virtio_writew(val, a) mmio_ops->mmio_writew((val), (a)) > > +#define virtio_writel(val, a) mmio_ops->mmio_writel((val), (a)) > > How exactly are these ops hooked up? I'm envisaging something like: > > ops = spec_compliant_ops; > [...] > if (firmware_says_hypervisor_is_buggy()) > ops = magic_qcom_ops; > > am I wrong?
If CONFIG_VIRTIO_MMIO_OPS is defined, then I expect this to be unconditionally set to 'magic_qcom_ops' that uses hypervisor-supported interface for IO (for example: message_queue_send() and message_queue_recevie() hypercalls).
> > +int register_virtio_mmio_ops(struct virtio_mmio_ops *ops) > > +{ > > + pr_info("Registered %s as mmio ops\n", ops->name); > > + mmio_ops = ops; > > Not looking good, and really defeats the point of standardising this stuff > imo.
Ok. I guess the other option is to standardize on a new virtio transport (like ivshmem2-virtio)?
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