[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH V4 23/24] libxl: Introduce basic virtio-mmio support on Arm
On Wed, 20 Jan 2021, Julien Grall wrote: > > > > +#define GUEST_VIRTIO_MMIO_SIZE xen_mk_ullong(0x200) > > > > > > AFAICT, the size of the virtio mmio region should be 0x100. So why is it > > > 0x200? > > > > > > I didn't find the total size requirement for the mmio region in virtio > > specification v1.1 (the size of control registers is indeed 0x100 and > > device-specific configuration registers starts at the offset 0x100, however > > it's size depends on the device and the driver). > > > > kvmtool uses 0x200 [1], in some Linux device-trees we can see 0x200 [2] > > (however, device-tree bindings example has 0x100 [3]), so what would be the > > proper value for Xen code? > > Hmm... I missed that fact. I would say we want to use the biggest size > possible so we can cover most of the devices. > > Although, as you pointed out, this may not cover all the devices. So maybe we > want to allow the user to configure the size via xl.cfg for the one not > conforming with 0x200. > > This could be implemented in the future. Stefano/Ian, what do you think? I agree it could be implemented in the future. For now, I would pick 0x200.
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